Text-book of modern carpentry; comprising a treatise on building-timber, with rules and tables for calculating its strength, and the strains to which each timber of a structure is subjected; observations on roofs, trusses, bridges, &c. and a glossary, explaining at length the technical terms in use among carpenters

tJL

THE LIBRARY

OF

THE UNIVERSITY
OF CALIFORNIA

PRESENTED BY

PROF. CHARLES A. KOFOID AND
MRS. PRUDENCE W. KOFOID

TEXT-BOOK

OF

MODERN CARPENTRY;

A TREATISE ON BUILDING-TIMBER,

WITH RULES AND TABLES FOR CALCULATING ITS STRENGTH, AND THE
STRAINS TO WHICH EACH TIMBER OP A STRUCTURE

is SUBJECTED;

on glaofs, Crosses, Sribgts, ttc.

A GLOSSARY,

EXPLAINING AT LENGTH THE TECHNICAL TERMS IN USE AMONG
CARPENTERS.

BY THOMAS W. SILLOWAT,

EllustrateH trg (Tfomtg (Copperplates.

BOSTON:

CROSBY, NICHOLS, AXD COMPANY,

117, WASHINGTON STREET.

1858.

r/iy

Entered, according to Act of Congress, in the year 1858,

BY THOMAS W. SILLOWAY,

In the Clerk's Office of the District Court of the District of
Massachusetts.

BOSTON:

PRINTED BY JOHN WILSON AND SON,
22. SCHOOL STREET.

PREFACE.

THE following work has been prepared as a book
of reference for the master-carpenter, and as a
manual of instruction for the journeyman and the
apprentice. The costliness of the works of Beli-
dor, Rondelet, Tredgold, and others, places them
beyond the reach of mechanics of ordinary means ;
and, being written with reference to scientific for-
mulas, cannot be appreciated, or even understood,
except by those versed in mathematics. Having
in view the interests of the large and important
class above named, we have scrupulously avoided
such abstruse algebraic and mathematical formulas
as would more properly belong to an encyclopaedia
of the science.

Works of distinguished authors have been con-
sulted, but nothing selected which did not commend
itself as of immediate practical utility ; and, while
the advanced student may perhaps regret the
absence of the higher mathematics, it is presumed
that their omission removes a great obstacle to
the progress of the less learned, though not less
worthy, mechanic. An extended essay on Car-

M363539

iv PREFACE.

pentiy as a science being rendered unnecessary
by the comprehensive nature of the work, its place
is, we think, more properly occupied by such prac-
tical suggestions as have been considered most
useful. Practice and experience, those great and
successful teachers of all truth, are the privilege
of every mechanic ; but the lessons which they
convey, while perhaps sufficing for his ordinary
labors, may be greatly lightened, and far more
worthily directed, by a careful study of those
results of the experience and science of others,
which it is the aim of this work to embody and
explain.

The portion of this treatise devoted to building-
timber states an average of results arrived at
through many experiments and much observation.
The authorities on the subject are many, and the
field wide. It is, however, believed that the few
pages allotted to the subject comprehend nearly
all that is of practical value in the works of Hut-
ton, Barlow, Du Hamel, Perronet, and many other
writers both in Europe and America.

The illustrations are intended not only to exem-
plify the principles of the art, but also to suggest
examples for imitation ; and the amount of success
attending our efforts in selection — at all times a
work of much difficulty — must be judged of by
the reader. He will, however, bear in mind that
it has been an important consideration to give a
variety of each kind of work in a small compass.

PREFACE. V

The " Glossary," which forms so large a part
of the text, is the result of much labor, and, it is
hoped, may prove of corresponding value.

Our work is now presented to the public in the
belief, that, notwithstanding its imperfections, it
contains a sufficient amount of information to make
it a desirable companion to the apprentice in his
hours of study, as well as a ready assistant to the
man of business ; and, in this hope, it is respect-
fully dedicated to their service.

THOS. W. SILLOWAY.

BOSTON, May, 1858.

CONTENTS.

Page.
CARPENTRY 1

Nature and Properties of Timber 6

Kinds of Timber in use 12

Foreign Timber 21

Felling Timber 24

Seasoning Timber 30

Preservation of Timber 33

Durability of Timber .38

Strength of Timber 41

Rules for determining its Tensile Strength .... 45

„ „ „ „ Cross-strength 52

» » n » Compressive Strength . . 59

GEOMETRY 65

Square Hoot 77

EQUILIBRIUM OF STRAINS ox TIMBER 81

SCARFING TIMBERS 91

FLOORS 95

TRUSSED BEAMS 98

yiii CONTENTS*

Page.

ROOFS 103

Observations on Eoofs 103

Timbers employed in Eoofs 107

Iron-work employed in Roofs 112

Heavy Roof-trusses 119

DOMES .124

BRIDGES 129

ARCH-CENTERINGS 134

JOINTS IN FRAMING 139

IRON . 141

Tables for calculating the Weight of Iron-work . . 143
TABLES FOR CALCULATING THE QUANTITY OF TIMBER

IN ANY GIVEN STICK 147

GLOSSARY 159

CARPENTRY.

THE Art of Carpentry is one of the leading
parts of the sciences of architecture and en-
gineering. It has claimed and received the atten-
tion of the masters in those sciences, and must
always be a subject worthy of scientific considera-
tion. No unimportant portion of the writings of
Delorme, Palladio, and even Vitruvius, js that
which relates to the art under consideration. The
frame of a building sustains the same relation to
the whole edifice that the bones of the system do
to the human body.

It is a self-evident truth, therefore, that a know-
ledge of carpentry, as a science, is of great import-
ance to the builder ; for no edifice can be properly
constructed but in accordance with those rules and
principles to which the art is subject. Walls of
stone or brick may not for their construction
demand this information ; still, to all buildings

2 CARPENTRY.

there must be roofs, floors, and partitions, to con-
struct which the art of carpentry will be employed.

The first and most important thing to be con-
sidered, in making or executing any design, is the
end to be attained. If a roof is to be produced, it
is not enough to know the span and the pitch, but
it is quite as essential to know the material with
which it is to be covered ; the design best adapted
for the purpose ; whether the determined inclina-
tion is best for that particular covering, &c. If
a floor is to be built, the carpenter is to consider
the purpose for which it \vill generally, or may
possibly, be used ; if a partition is to be erected,
what support it may have or may lack below, what
weight may rest upon it, and to what side-strains it
may be subjected.

It is, however, unnecessary to enumerate, since
it is plain, that, before commencing any work, it is
important to see the end as well as the beginning.

The next consideration is so to select both mate-
rials and design as to make the best possible use of
the means employed. This can be done effectually
only by the application of such rules as investiga-
tions have proved of value. A knowledge of the
nature and properties of the kind of timber used,
its strength and durability, the strains to which it

CARPENTRY. 3

will be subjected, and many other things of like
nature, are of much moment in the successful prac-
tice of the art. It was a wise remark of Sir Tho-
mas Seppings, that "the strength of a piece of
framing, whatever may be the design, can never
exceed that of its- weakest parts; and a partial
strength produces general weakness."

The third consideration is in regard to construc-
tion itself. This science, like all others in which
are involved mechanical principles, has many
parts, each of which is closely interwoven with the
others. Most authors have divided the art into two
parts. One is called mechanical carpentry, and
treats of the nature and properties of timber ; the
other, practical carpentry, or the use of timber.
The division is, to a good degree, warranted : yet
they are mutually dependent ; and, in order to
make a knowledge of one useful, it is necessary
to understand both.

Having determined the things suggested, and, in
addition, such incidentals as may be connected with
them, the next step is to execute the work. The-
ory must now give place to practice ; and what
exists but on paper, or in the imagination of the
artificer, is to be produced as a thing of life. To
one who has thoroughly informed himself on the

4: CARPENTRY.

principles involved in the work he is to do, this
part of his labor will not be without a correspond-
ing degree of satisfaction and entertainment : for to
execute a design is, or may be, as inspiring as it
was to conceive and project it ; and it is a question
of some nicety to determine, whether the architect
and the engineer experience more real pleasure in
witnessing a design as it is wrought out and pro-
duced, than the mechanic, who, by care and labor,
gives to comparatively crude and unfashioned ma-
terials condition and form which endow them
with a power —

" That flings control
Over the eye, breast, brain, and soul ;
Chaining our senses to the stone,

Till we become

As fixed and dumb
As the cold form we look upon."

There are many things essential for the attain-
ment of the desired end ; but the most important
of them all, and, in fact, the great and govern-
ing principle involved throughout, is, that the
workman understand well every part of his work,
and that he be possessed of a desire to excel in his
profession. In this, as in all arts, "knowledge is
power." The advice of Mr. Tredgold is apt, and
to the point. He says, " Nothing will assist the

CARPENTRY. O

artist more in forming a good design than just con-
ceptions of the objects to be attained ; and nothing
will render those objects more familiar to the mind
than drawing them."

To make enlarged copies of the designs published,
and at the same time to study with care the rules
which govern them and the principles that are
involved, will insure success to any one who may
be disposed to make the attempt.

NATURE AND PROPERTIES OF
TIMBER.

TIMBER is the substantial substance of all trees.
"Woods differ in their properties ; some being tough
and hard, while others are brittle or soft. They
are, therefore, of value proportional to the kind of
work for which they are required. A great variety
of opinions exists in regard to the manner in which
wood is formed. All are, however, agreed, that
the trunk and branches of trees are composed of
three parts, — the bark, the wood, and the pith.

The BARK is a covering which incases the entire
wood, and is composed of three distinct parts, —
the Epidermis, the Cellula, and the Liber.

The EPIDERMIS is a thin skin, being the extreme
outer covering.

The CELLULA is the organic matter next inside
the Epidermis. It answers to the flesh of animals,
and is formed into an infinite number of tubes.

PROPERTIES OF TIMBER. 7

The LIBER is the inner or newly formed bark.
The Epidermis and the Liber together form what
is called the Cutis, or outer bark, the Liber being
the inner.

The WOOD is the material that exists between the
pith and the bark, and is of two kinds, — the heart-
wood, or Duramen ; and the sap-wood, or Alburnum.

The HEART-WOOD is the hard and dark part
next the pith.

The SAP-WOOD is that which is between the
heart-wood and the bark.

The PITH is the soft and spongy substance which
is enclosed by the heart-wood at its centre.

In all new shoots, the pith and bark are in con-
tact, without wood between them ; but, as the shoot
extends, it enlarges by the deposit of a secretion
called cambium, which lies in a cylindrical ring
between the pith and the bark. The deposit thus
made is of two kinds. One is formed into bark,
and the other ultimately hardens into wood. A
deposit of this nature is made annually ; and, if the
trunk of a tree be cut off across the fibres of
the wood, the surface will present a series of con-
secutive layers or rings, so that one is enabled to
determine by their number the age of the tree in
which they exist

8 PROPERTIES OF TIMBER.

It is unusual to find any two rings that are alike,
either in regard to their whole thickness, or the
proportion of the solid part to the porous ; the di-
mensions and proportion being governed by the
amount and nature of the deposit, some years being
more favorable to each respectively than others.

So exact are the laws by which this is governed,
that the part of the rings on the north side of
trees is thinner, making the heart-wood nearer
the north side. This results from the fact, that, the
south side being more exposed to the action of
the sun, the pores are expanded, and a larger
quantity of sap is transmitted through that side.

The wood of no tree is entirely solid, but is filled
with tubes, or pores ; and the only substance of a
solid nature that exists is that which forms the
walls of the cells before named. These vessels
are designed for the conveyance of a fluid called
sap, which is absorbed by the roots, and passes up
through the pores of the wood to the leaves, where
it undergoes a chemical change, and is then re-
turned through the cellula, or porous part of the
bark.

Sap, when it leaves the roots, is very limpid,
being nearly as thin as water : but, as it passes up
through the pores, it either meets with a substance

PROPERTIES OF TIMBER. 9

which it dissolves and carries along with it, or, when
it arrives at the most distant parts, is condensed ;
for, on its return, it is thickened; and entirely
changed in its nature.

As it passes downward through the cellula, it
gradually deposits a large proportion of the mate-
rial it contains ; so that, when it arrives at the
roots, it is as thin as when it started to pass up-
ward.

As soon as the leaves are developed, sap ceases
to flow. The deposit gradually hardens ; and
thus is formed a new layer of material for wood
and bark. From this period till near autumn, ve-
getation ceases ; but, after this, the sap is again in
motion, and, as it passes up, deposits along the
pores of the wood the substance which the ascend-
ing sap of the next spring will dissolve and carry
along for the formation of the new wood and leaves.
As the tree increases in diameter, the wood at the
centre is compressed by the growth of the new
wood ; and, becoming more solid, the pores decrease
in size, and hence but little sap will flow through
them. The part nearer the bark, being less com-
pressed, is soft and porous ; and, as the larger part
of the sap passes through it, it takes its name sap-
wood.

10 PROPERTIES OF TIMBER.

Those parts of the tree which need to be elastic
and porous are continually receiving new substance
of a proper nature for its replenishment ; while, at
the same time, those which are compressed into
hard wood serve to give the requisite and additional
support, or back-bone, to the increased tree. It has
been well remarked, that the life of a tree is like
that of a man, and may as properly be divided into
three periods, — infancy, maturity, and old age.

During the whole of the first period, the tree
continues to increase. Through the second, it
simply maintains itself, and neither loses nor gains.
As soon, however, as the heart-wood begins to
decay, the second period ends, and signs of old age
soon appear : and the comparison is not then inapt ;
for like an old man who seems to be still fresh
and vigorous, but whom one storm of disease may
break and sweep away, so often does a venerable
and revered oak, clinging still to life, as if loath to
die, put on, with each returning spring, " its youthful
robes anew." But, its heart diseased, and vitality
expended, being engaged in some tempestuous hour
in an unequal contest, it falls to rise no more.

The timber of all trees partakes, to a greater or
less degree, of the nature of the soil on which it
grows. Trees grown on soft and spongy soil usually

PROPERTIES OF TIMBER. 11

produce wood that is comparatively soft and irregu-
lar in fibre. Therefore, if oak be grown on dry
and good land, the wood will be solid arid tough ;
but, if grown on soft and wet land, it will be pro-
portionally poor, and of less value. This fact is
true of all timber-trees.

The wood of trees which stand alone, or where
there are but few, and those scattered, is better
than that grown in the middle of a forest, where
it is not exposed to the sun and air. Hence, for
building purposes, those trees which stand alone are
to be first selected.

It may be well to mention here, that if the soft-
wood trees are very large (as is often the case with
some of the pines), and most of the branches are
near the top, the wood near the base of the trunk
is sometimes found to be shaky. This defect is
produced by the action of heavy winds on the top
of the tree, which wrenches or twists the but, and
thus cleaves apart the fibres of the wood.

12

BUILDING-TIMBER.

THERE are but five kinds of wood in common use
for carpentry in this country. These are spruce,
pine, oak, hemlock, and chestnut.

SPRUCE (Abies) is indigenous to the colder parts
of North America, where it grows in great abun-
dance. For most qualities which constitute good
framing-timber, it is excelled by no other wood in
use.

There are two varieties, which are familiarly
known as black or double (Pinus niger) and white
or single spruce (Pinus alba). Of these, the black
is of most value ; it being much tougher than the
white, and may be procured in much larger sticks.
The foliage of this variety is darker and heavier.
The white spruce is of a comparatively small
growth ; but the wood may be worked much
smoother than the other variety. Spruce-wood,
when seasoned, is of a clear yellowish white, the

BUILDING-TIMBER. 13

annual rings being distinctly marked by a darker
tint of the same color, and having a silk-like lustre.
A cubic foot, when seasoned, weighs thirty-one
pounds and a half. It shrinks, in seasoning, about
a seventieth part of its dimensions, and loses a
fourth of its weight.

The principal defects of this wood are its liability
to twisting and splitting in the sun, and its ten-
dency to decay in all damp situations ; but where
due attention is paid to these points, and proper
care is exercised to prevent the exposures named,
little else need be done to insure the permanency
of work composed of this wood.

PINE (Pinus) is next in value as material for a
frame. Of this wood, there are many species.
The family ( Conifera) to which it belongs is large,
and comprises all that ranges from the most com-
pact and hard spruce to the softest white pine.
But two kinds, however, will claim our attention ;
the others, as framing-timber, partaking largely
of the nature of spruce. Remarks relating to that
wood may be applied with nearly the same pro-
priety to all the harder varieties of pine.

The two varieties most in use are known as
white pine and Carolina pine.

WHITE PINE (Pinus strobus) abounds in all the

14 BUILDING-TIMBER.

northern portion of the United States, and is
the tallest of our native trees. It is remarkable
for the straightness of its trunk, which is often
found a hundred feet high, entirely clear of limbs.
The whole tree frequently attains an altitude of
two hundred feet. It is the same as that known in
England as Weymouth pine. In forests, all except-
ing the top branches decay early ; and these, being
above all other trees, make it conspicuous as far as
it can be seen. Pine is of rapid growth, and, in
favorable situations, increases an inch in diameter,
and two feet in height, in a single year. The bark of
trees which are less in diameter than fifteen inches is
very smooth, and of a bottle-green ; being, through
the warm season, covered with an ashy gloss.

The color of the seasoned wood is a brownish
white. A cubic foot weighs twenty-four pounds
and three-quarters. Its decrease of dimension in
seasoning is slightly more than spruce.* It has
little tendency to warp or twist ; and, for such parts
of a frame as are liable to be exposed to dampness
and continued wet, it is preferable to spruce. The
wood being softer, it is more liable to indentation

* It is the generally received opinion of carpenters, that all
wood is liable to some shrinkage in length; though, in most
instances, it is hardly perceptible.

BUILDING-TIMBER. 15

at the joints ; and, being less stiff, it is not, for
general purposes, entirely equal to spruce. As a
whole, its average value for framing purposes may
be considered as nine to ten.

For finishiny-lumler, it excels all others, and
sustains the same relation to joinery that spruce
does to carpentry. None is better calculated to
withstand the effects of the sun and weather than
this ; for with the exercise of proper care in sea-
soning, and reasonable protection afterwards, it will
retain its natural strength and vigor as long as the
best of oak.

CAROLINA PINE (Pinus australis) is, in most
respects, entirely unlike the wood last described;
being very compact, and thoroughly saturated with
a resin, or pitch, which is remarkable for its intense
fragrance. It grows in great luxuriance in all our
States south of Virginia, and is familiarly known
at the north as southern pine. Timber of almost
any reasonable length and dimensions may be easily
obtained. This wood is seldom cut up into small
joists ; but, when not sawed into large framing-
timber, it is used for planks and floor-boards ;
the solidity of the wood, and the fineness of its
grain, making it of great value for the purpose
last named.

16 BUILDING-TIMBER.

In all dry situations, it is exceedingly durable ;
but, in wet or even damp places, it loses its vigor,
and soon moulds and decays. Its tensive strength,
compared with oak, is nearly equal ; while its weight
is much less. This quality, added to its peculiar
stiffness and resilience, has of late years made
it a rival of oak, where a lighter yet solid wood is
required. It is, however, very brittle, and liable
to fracture by a sudden blow or concussion ; making
it inferior to oak, where toughness is needed.

This wood, when newly planed, is a rich yellow ;
the resinous parts giving it a finely variegated ap-
pearance. The average weight of a cubic foot,
when seasoned, is not far from thirty-eight pounds
and a quarter. It decreases a fifth of its weight
in seasoning, and a sixty-fifth of its dimensions ;
shrinking something more in the direction of its
length than either of the other woods in common
use.

OAK ( Quercus) is a wood, like all others, exist-
ing in many species. Only two, however, — those
commonly known as white oak and yellow oak, —
are in general use for building purposes. It is a
native of temperate climates, and is found in great
perfection and vigor in the United States, — from
Virginia (the northern limit of the growth of Ca-

BUILDING-TIMBER. 17

rolina pine) to the Canada line. The wood is very
durable, when kept immersed in water ; and, while
remaining in a perfectly dry situation, it has lasted
more than a thousand years. When subjected
alternately to the action of water and air, together
with more than ordinary warmth, it is subject to
early decay. Oak-wood is hard, yet elastic and
tough. Its texture is alternately porous and solid ;
the porous sections being the lighter colored por-
tion of the annual ring. The wood of young
trees is much tougher than that of old ones, and
is more difficult to work. That of old ones is
often quite brittle ; while at the same time, in
most other respects, it appears to retain its natural
qualities. It is the case with oak as with all
trees, — that the wood, taken from the body and
large limbs, is stronger than that taken from
the small branches. The sap is possessed of a
peculiar odor and taste. It contains gallic acid;
and, in consequence, turns black or purple, when
brought in contact with iron.

The color of the wood is a whitish brown in the
white species, and a yellowish brown in the yellow.
A cubic foot, when dry, weighs forty-eight pounds.
It shrinks, in seasoning, a thirty-sixth part of its
dimensions, and loses a third of its weight.
2

18 BUILDING-TIMBER.

For many purposes, — such as strengthening-
pieces, keys, treenails, &c., — oak is indispensable ;
though of late years, as a general framing-timber,
it has been little used. For the first two centu-
ries after the settlement of this country, it was
employed almost to the entire exclusion of other
wood ; but spruce and pine have gradually sup-
planted it, till now a new piece of oak-framing is
but seldom seen. When used to any great extent,
it is for open timber-roofs of churches, or some-
thing of the kind. The natural beauty of its se-
lected wood for a rich finish-lumber, and its great
strength and durability as a framing-timber, insure
the usefulness and value of the " monarch of the
forest."

In addition to the foregoing, the two next in
value are those familiarly known as the black oak
and the live oak. The former is nearly allied to
the yellow oak ; and is, in many respects, of equal
value. Live oak is principally used in ship-
building. The wood is nearly identical with white
oak; but the nature and habits of the tree tend
to produce only small and very crooked timber.
For the various purposes, however, for which the
timber is used, it is an important member of
the Quercus family.

BUILDING-TIMBER. 19

HEMLOCK (Canadensis) is often used in the
cheaper kinds of carpentry. It is indigenous to
nearly all places which are favorable to the produc-
tion of spruce and the light pines. In dry situations,
when the wood has been properly seasoned, and is
carefully protected from the action of the sun, it
may be considered as a fourth-rate wood. Its pe-
culiar structure, tending to twistish or cleftish grain,
makes it entirely unreliable for large timbers where
either tensile or compressive strain is required.
It decays quickly in damp situations ; and, if
exposed while in an unseasoned state, its heart-
wood cleaves from the surrounding wood by the
action of either sun or wind.

Considering these tendencies (existing even in
the best specimens), it is usually cut into small
studding-joists or common boards. Hemlock pos-
sesses one quality in common with oak and the
other hard woods ; viz., the tenacity with which it
adheres to a nail. An ordinary tenpenny cut nail,
if driven into the wood half its length, will part
before it can be drawn out. This quality is one
of its first recommendations for common or rough
boarding, as it firmly holds the nails of shingling,
slating, clapboarding, &c.

The sap is possessed of an intense and some-

20 BUILDING-TIMBER.

what unpleasant odor. It is unfit for use while
in an unseasoned state, as it corrodes iron im-
mediately at the part where it begins to project
from the wood. The color of the wood is a light
brown ; and a cubic foot, when dry, weighs twenty-
seven pounds. It shrinks, in seasoning, a little
less than spruce, and loses one-fourth of its
weight.

CHESTNUT ( Castanet) is a wood of great value,
and is in most respects nearly identical with oak,
which it resembles in color, toughness, and solidity.
It is a native of temperate regions, and is usually
found growing side by side with its rival. For
most purposes for which oak is used, chestnut is
of equal value. While exceedingly durable in
damp situations, it is equally so in those which are
dry ; and, in places partaking at times of both, it
.is preferable to oak. For posts set in the ground,
it may be considered good for a service of forty
years. Like oak, the grain of the wood is com-
pact ; and that of young trees is very tough and
flexible: but old wood is liable to brittleness, ap-
pearing sound and healthy without, while within
it is decayed and rotten. Chestnut contains one
valuable quality not possessed by either of the
other woods ; namely, when once seasoned, it is

BUILDING-TIMBER. 21

but slightly susceptible of shrinking or swelling.
The weight of a cubic foot of the wood, when per-
fectly seasoned, is forty-one pounds.

FOREIGN TIMBER.

As many scientific experiments have been made
in Europe on woods which are, in their general
properties and strength, nearly identical with those
in common use in America, a brief synopsis of
these will be given, that the carpenter may avail
himself of the experiments by applying the results
to our corresponding timber.

ACACIA (Robina), — a wood commonly known
in America as locust. A cubic foot, when seasoned,
weighs forty-eight pounds. It is slightly stronger
than oak.

CHRISTIANA DEAL (Pmus abies), — a wood
nearly allied to the spruce of North America.
It is somewhat heavier and tougher. It will
bear one-fifth more strain, and is also one-fifth
stiffer.

COWRIE (Dammara australis), — a New-Zea-
land tree, the wood of which answers well to the

22 BUILDING-TIMBER.

pitch or yellow pine growing in the New-England
States. A cubic foot, when seasoned, weighs
forty pounds. Its general strength is that of our
spruce.

DANTZIC OAK is of the same stiffness as our
white oak, but is tougher and stronger.

ENGLISH OAK (Quercus robur) is one-tenth
lighter, and one-seventh stronger, than our white
oak; and, while it is one-fourth tougher, it is not
as stiff by one-SBventh.

MAR-FOREST FIR (Pinus sylvestris), — a wood
which, in New England, would be considered as a
cross between spruce and northern pitch-pine. A
cubic foot, when dry, weighs thirty-eight pounds.
It is of the same tensile strength as our spruce,
but less elastic.

MEMEL FIR, — a wood nearly identical with
that from Mar Forest. It answers well to the red
and yellow pines of New England, but partakes
of the nature of spruce, in being stiffer than the
pines named.

NORWAY SPRUCE (Pinus abies) is, in many
respects, like our black spruce. It is harder, and
has more pitch. "When seasoned, it weighs thirty-
four pounds to a cubic foot.

RIGA OAK is one-seventh stronger than our

BUILDING-TIMBER. 23

white oak, but is one-seventh less stiff. It is one
of the toughest varieties of oak in use.

SCOTCH FIR is nearly identical with our New-
England red and yellow pine.

WEYMOUTH PINE (Pinus strobus) is a wood
identical with the white pine of New England.

FELLING TIMBER.

THE felling of timber was looked upon by ancient
architects as a matter of much moment. Vitru-
vius was so minute in giving advice on this subject,
as to urge that timber should never be felled but
in the decrease of the moon; and we find good
Isaac Ware saying of the suggestion (it being what
he termed the opinion of the " Roman oracle "),
" This has been laughed at, and supposed to be an
imaginary advantage. . . . There may be good in
following the practice ; there can be no harm : and
therefore, when I am to depend upon my timber, I
will observe it." Sir John Evelyn quaintly says,
" It should be in the vigor and perfection of trees
that a felling should be celebrated."

'The end to be attained in the management of
timber-trees is to produce, from a given number,
the largest possible amount of sound and durable
wood.

FELLING TIMBER. 25

To accomplish this requires not only attention
in felling the timber, but in caring for it after-
wards. The first, and perhaps most important,
advice is to fell a tree as near the time of its
maturity as possible : for, if it be cut earlier, the
sap-wood predominates ; and, the heart-wood being
comparatively soft, the timber cannot possess great
strength or much durability. If permitted to
stand long after this, it declines in quality; the
wood by degrees losing its elasticity, and becoming
brittle.

It is somewhat difficult to decide just when a
tree is at maturity. From the investigations of
naturalists, however, it may be safe to consider,
that hard-wood trees, as oak and chestnut, should
never be cut before they are sixty years old ;
the average age for felling being a hundred years.
For the soft woods, — as spruce and pine, — the
proper age is seventy years. It should be remem-
bered, that the times mentioned are by no means
arbitrary ; for situation, soil, &c., have much to do
with it.

When a tree, under conditions favorable to its
growth, entirely ceases increasing the diameter of
its trunk, and loses its foliage earlier in the autumn
than it is wont to do, these facts may be considered

26 FELLING TIMBER.

as indications of decline, and that the tree is of
sufficient age to be felled.

The next consideration is the season of the
year most favorable for the work. All investi-
gations tend to prove that the only proper time
is that at which the tree contains the least sap.
As stated in another article, there are two seasons
in each year when the vessels are filled. One is in
the spring, when the fluid is in motion to supply
nutriment to the leaves, and deposit material for
new wood : the other is in the early part of the
autumn, when, after the stagnation which gives
the new wood time to dry and harden, it again
flows to make the vegetable deposits in the vessels
of the wood. At neither of these times should
trees be felled ; for, if the pores be full of vege-
table juices, — which, being acted upon by heat and
moisture, may ferment, — the wood will decay.

In the New-England States, August is, for this
purpose, the best month in the year ; for, at that
time, most of the fluids and vegetable matter
having been exhausted in the formation of leaves
and wood, and the watery parts evaporated, the
wood is dryest. Next to this is the month of
January ; for then, as in August, there is but little
sap in the tree.

FELLING TIMBER. 27

The age at which trees should be felled, and the
most suitable time for the work, having been deter-
mined, there are two other things which claim at-
tention.

The first of these is the removal of the bark
from the trunk and principal branches of the trees.
This practice has, from time immemorial, been
considered of inestimable value : for, bj it, the
sap-wood is rendered as strong and durable as
the heart-wood ; and, in some particular instances,
experiments have shown it to be four times as
strong as other wood, in all respects similar, and
grown on the same soil, but felled with the bark
on, and dried in sheds.* Buffon, Du Hamel, and,
in fact, most naturalists, have earnestly recom-
mended the practice. The venerable Evelyn, in
his " Sylvia," says, " To make excellent boards and
planks, it is the advice of some, that you should
bark your trees in a fit season, and so let them
stand naked a full year before felling."

In regard to the time that should elapse between
the removal of the bark and the felling of a
tree, a variety of opinions exists. It was the usual
custom of early architects to remove the bark in
the spring, and fell the trees the succeeding winter.
* Emerson's " Trees and Shrubs of Massachusetts," p. 33.

28 FELLING TIMBER.

Later investigations have proved that it is better
to perform this work three, or even four, years
in advance, instead of one. Trees will, in most
situations, continue to expand and leaf out for
several seasons after the bark has been removed.
The sap remaining in the wood gradually becomes
hardened into woody substance ; thereby closing the
sap-vessels, and making it more solid. As bark
separates freely from the wood in spring, while
the sap is in motion, it should be taken off at
that period.

The second suggestion is to cut into and around
the entire trunk of the tree, near the roots, so
that the sap may be discharged ; for, in this manner,
it will be done more easily than it can be by
evaporation after the tree is felled. In addition
to this, if it be permitted to run out at the incision,
a large portion of the new and fermentable matter
will pass out with it, which would remain in the wood
if only such material is removed as would pass off
by evaporation.

This cutting should be made in the winter pre-
vious to the August in which the tree is to be
felled ; and the incision should be made as deep into
the heart-wood as possible, without inducing a
premature fall of the tree.

FELLING TIMBER. 29

Many suggestions might be made as regards
the mechanical operation in felling trees : but, as
these are familiar to all intelligent workmen, we
will mention only one; namely, the value of re-
moving from the side of the tree such branches
as will strike the ground when it falls, and, by
wrenching, cleave the grain of the wood, and
thereby injure the timber. Such defects, which
are often found after the timber has become sea-
soned, could not be discovered when it left the
mill.

30

SEASONING TIMBER.

NOTHING contributes more to increase the value
of timber than thorough and judicious seasoning.
The principal objects to be attained are, first, to
remove the saccharine or loose vegetable matter,
which by heat and moisture may ferment, and
thereby cause the wood to decay ; and, second, to
remove all moisture, in order that the wood may
shrink to its smallest dimensions, and thus be en-
abled to retain its shape and place after it has been
wrought. To attain this, many methods have been
used ; but, fortunately, the most simple and practical
of them all is of most value. If timber be properly
subjected to the action of water and air, it may,
by this means, be perfectly seasoned, and at small
expense.

As soon as it has been felled, timber should be
immediately removed to the mill, and sawed. If
this is impracticable, and the bark has not been

SEASONING TI3IBER. 31

removed, it should be taken off, and the logs put
into the river or some running stream, there to
remain till they can be taken to the mill.

If no stream is near, they should be placed on
some dry spot, be well blocked up from the ground,
and covered with boughs of trees to keep from
them the action of the hot sun or of strong cur-
rents of wind.

After the lumber has been sawed, it should be
put into the water, and chained down beneath its
surface, for at least two weeks, when the vegetable
matter will be dissolved, and pass out into the
water. After remaining submerged for the time
named, it should be taken out, and piled in a dry
place, where it may be covered with boards to
protect it from the direct action of both sun and
wind.

It is not well to attempt to dry it too quickly ;
for, if it be subjected to great heat, a large portion
of the carbon will pass off, and thereby weaken the
timber. And, further, if it be dried by heat,
the outside will become hardened, and the pores
closed ; so that moisture, instead of passing out,
will be retained within. Timber, too suddenly
dried, cracks badly, and is thus materially in-
jured.

32 SEASONING TIMBER.

In piling it, the sleepers on which the first pieces
are laid should be perfectly level and "out of
wind," and so firm and solid throughout, that they
will remain in their original position ; for timber,
if bent or made to wind before it is seasoned, will
generally retain the "same form when dried. Pieces
of wood should be put between the sticks, and each
piece directly over the other, so that air may freely
pass through the whole pile ; for, while it is neces-
sary to shield timber from strong draughts of wind
and the direct action of the hot sun, a free cir-
culation of air and moderate warmth are equally
essential.

More costly methods of seasoning — such as
smoking, steaming, exhausting the sap by an air-
pump, &c. — are not sufficiently valuable to com-
pensate for the trouble and expense.

The length of time requisite for seasoning tim-
ber depends entirely upon the size of the stick, the
kind of wood, its situation, &c., while drying. The
carpenter should exercise his own judgment ;
always remembering that a large stick is never so
dry that it will not season, and consequently shrink
still more, if sawed into smaller pieces, and new
surfaces be exposed to the action of the air.

33

THE PRESERVATION OF TIMBER.

To preserve timber is next in importance to ob-
taining it ; for, unless properly cared for, however
good may be the material, all previous precautions
avail but little. Wood is liable at any time to
change its nature, and part with its most valuable
properties. In all timber, even if well seasoned,
there remains a certain quantity of sap and vege-
table matter, which, when the piece is shut up in
stagnant air liable to be heated in summer, will
mould or ferment, and an acid be formed, decom-
posing the wood.

In no instance should a piece of framing be so
enclosed that fresh air cannot at all times come in
contact with it. To every roof, church-spire, dome,
&c., there should be air-holes at such points above
and below as will insure a continual circulation of
air about the wood.

The next consideration is to protect it from the

34 THE PRESERVATION OF TIMBER.

action of alternate moisture and dryness. If a
stick of timber be exposed to a continued heat, —
as, for instance, over a baker's oven, — it will in
time lose its elastic power, and become brittle.
If, on the other hand, a piece of the same timber,
in all respects identical in properties and nature,
be immersed in water, and remain submerged, it
will retain the larger part of its properties for
centuries. In fact, if not injured by insects or
acids in the water, it may be considered as almost
indestructible ; but the reverse of this is the case
if it be subjected to the alternate action of water
and air.

As soon as a piece of wood is exposed to the
action of moisture, the vegetable and saccharine
matter begins to dissolve; and a slimy coating is
formed wherever the solution exists. When ex-
posed to the air, this slime ferments ; and from it
grows a sort of fungus, which lives on the vital
parts of the wood itself. A continual series of
exposures of this kind soon induces a visible de-
cay, which ends in the entire destruction of the
timber.

Every part of a frame should in some way be
protected. No work should, therefore, be placed
on or very near the ground, where earth can in

THE PRESERVATION OF TIMBER. 35

any way come into immediate contact with it ;
nor should any be subjected to the direct action
of steam or vapor, without being in some way
shielded. The artificial methods of preserving
timber are numerous. Covering the work with
boards is in many instances effectual. Sometimes,
however, this is no protection, but, on the con-
trary, serves to retain moisture that would evapo-
porate if left exposed, as is often the case with the
sills of buildings, timber-bridges, &c.

In every instance where the timber must be
covered, but is necessarily exposed to moisture,
also when it is exposed to the action of the weather
without a covering, artificial means for preservation
must be resorted to.

The first step to be taken is to season the tim-
ber thoroughly. When this has been done, the
whole of the exposed surfaces should be covered
with some preparation that will strike into the
wood, and, as much as possible, harden the outside.
Thus, by closing the pores, the piece is made im-
pervious to the weather.

A valuable practice for the preservation of tim-
ber is to heat it by burning charcoal, or something
of like nature, beneath ; and, while it is in a heated
state, applying a hot solution of an ounce and a

36 THE PRESERVATION OF TIMBER.

half of corrosive sublimate, or one of aqua fords
(nitric acid), in a gallon of water. After this is
done, and the work well dried, it should be painted
with the best quality of white lead and oil.

A thin solution of hot coal-tar and whale-oil is
of great benefit to all timber that is to be placed
near the ground. If this operation be repeated
two or three times, and finely pulverized clinkers
from a blacksmith's forge, or the dust made from
the scales of iron which lie about an anvil, be sifted
upon the timber while the tar is newly put on, it
will possess great durability, since wood prepared
in this manner is scarcely susceptible of decay.

Pyroligneous acid, or the liquor that drips from
stove-pipes in which vapor condenses, also strong
decoctions of soot applied hot, are recommended as
good preservative agents. In all framing exposed
to the weather, every mortise that can hold water,
and their tenons, together with all the wood about
them, should have a good coating of one of the
preparations first named, before the work is put
together.

It not unfrequently occurs that the wood at the
lower end of posts, rafters, &c., of church-steeples,
is found to be entirely decayed, while other parts
of the structure are perfectly sound. In almost

THE PRESERVATION OF TIMBER. 37

all such cases, some part of the work, being imper-
fect, has admitted water, which, following down the
post to its end, has -filled the mortise, and thus
rotted the wood.

When a piece of framing is to be permanently
exposed to the weather, it should be treated with
one of the solutions first described, and then tho-
roughly painted and sanded. Wood in a proper
condition when felled, afterwards thoroughly sea-
soned, well saturated with diluted corrosive subli-
mate, and, finally, kept properly painted and sanded,
is as durable as it ever can be.

One caution it would be well to remember ;
namely, to refrain from applying paint or any
preparation to wood before it is thoroughly sea-
soned : for, should the outside be coated so as
effectually to prevent impenetration from without,
evaporation will also be prevented from within ;
therefore, all moisture that may be in the wood will
be retained, and rot the piece.

Another suggestion is to use timbers as small
as the nature of the work will permit. It is* a
mistake to suppose that large timbers will continue
good longer than small ones. We may see an
exemplification of this at any New-England farm-
house. The light spokes of a wheel will remain

38 THE PRESERVATION OF TIMBER.

sound and strong for years after the tongue of the
cart to which they belonged has entirely decayed.

If a timber is sufficiently Strong when first used
(the requisite allowance being made for permanent
strain), all has been done that prudence would
dictate, since no increase of the dimensions of
the piece will insure its longer duration. And,
finally, it should be scrupulously remembered, that
timber will not certainly remain sound because
a large portion, or even most of it, is in proper
condition, and well cared for. Only so much as is
actually protected will retain its qualities ; and any
part so exposed as to injure the whole stick will
as surely injure or destroy the unprotected part.
Therefore, the ends of timbers which are built into
walls, also all surfaces in contact, — as where the
side or edge of one stick rests upon another, tenons
in mortises, &c., — should be supplied with air,
kept dry, and in every way properly protected.

DURABILITY OF TIMBER.

The durability of timber is almost incredible.
The following are a few examples for illustration,

THE PRESERVATION OF TIMBER. 39

being vouched for by Buffon, Du Hamel, Rondelet,
and others : —

The piles of a bridge built by Trajan, after hav-
ing been driven more than sixteen hundred years,
were found to be petrified four inches ; the rest
of the wood being in its ordinary condition.

The elm-piles under the piers of London Bridge
have been in use more than seven hundred years,
and are not yet materially decayed.

Beneath the foundation of Savoy Place, Lon-
don, oak, elm, beach, and chestnut piles and planks
were found in a state of perfect preservation, after
having been there for six hundred and fifty years.

While taking down the old walls of Tunbridge
Castle, Kent, there was found, in the middle of a
thick stone wall, a timber-curb, which had been
enclosed for seven hundred years.

Some timbers of an old bridge were discovered,
while digging for the foundations of a house at Dit-
ton Park, Windsor, which ancient records incline us
to believe were placed there prior to the year 1396.

The durability of timber out of the ground is
even greater still. The roof of the basilica of
St. Paul, at Rome, was framed in the year 816;
and now, after more than a thousand years, it is
still sound : and the original cypress-wood doors

40 THE PRESERVATION OF TIMBER.

of the same building, after being in use more
than six hundred years, were, when replaced by
others of brass, perfectly free from rot or decay ;
the wood retaining its original odor. The timber-
dome of St. Mark, at Venice, is still good, though
more than eight hundred and fifty years old. The
roof of the Jacobin Convent at Paris, which is
of fir, was executed more than four hundred and
fifty years ago.

The age of our country's settlement does not
enable us to refer to examples of like antiquity;
but no good reason appears to exist why timber
may not be as durable in America as in Europe.
Many old white-pine cornices here exist, which,
having been kept properly painted, have been ex-
posed to the storms of more than a hundred and
fifty years. The wood is still sound, and the
arrises are as good as when they were made ;
while freestone, in the same neighborhoods, has
decayed badly in less than fifty years.

STRENGTH OF TIMBER.

To discover rules which will in all cases determine
the exact strength of timber has for many years
been an object of interest with scientific men. Mr.
Tredgold, an eminent writer on the science of car-
pentry, has laid down at length the results of the
best investigations made by himself and others ;
but, in summing up, he speaks as follows: "The
age of trees at the time of cutting ; the natural
defects, such as knots, shakes, &c. ; also the mode
of seasoning, or the comparative dryness, — are
the cause of some difference in the strength and
stiffness of timber. All these things considered, it
is impossible to calculate correctly its strength and
stiffness." After reminding the reader that the
" precision which is so essential to the philosopher
is not absolutely necessary to the architect and
engineer," he says, " They content themselves with
approximations that are simple and easy to be

42 STRENGTH OF TIMBER.

obtained ; and, provided that the limits which can-
not be passed with safety be pointed out, these
approximations are sufficient to direct their prac-
tice." *

Mr. Peter Nicholson (from whose works subse-
quent authors have borrowed ad libitum) remarks
as follows : " On that subtile subject, — the propor-
tional strength of timber, on which I gave some
observations and calculations in my ' Carpenter's
Guide,' — I was in hopes that I should have been
able to reduce the theory of scantlings to an arith-
metical rule of consequences certain, and of general
application. I have to lament that all my endea-
dors, assisted by several gentlemen well versed in
mathematics, have hitherto been unsuccessful." t

Experiments on the strength of timber have,
until a late day, tended but little to reform the
science of carpentry. Probably more has been
done by bold, and perhaps rash, experiments than
by all the works which have been written. It
remains a fact, however, that the strength of any
piece of timber may be determined with sufficient
accuracy for all practical purposes. In the ex-

* Tredgold's " Elementary Principles of Carpentry," art. 68,
p. 29.

t " Carpenter and Joiner's Assistant," pp. vi. and vii. (Pre-
face).

STRENGTH OF TIMBER. 43

amples of framing published in this work, such
dimensions for the several timbers are given as
experience has approved ; and these examples
comprise all that any carpenter can need. But,
that he may be fully informed in regard to the
strength of the various kinds in common use, tables
and rules will be given, exhibiting the principles
involved. These tables have been prepared ex-
pressly for this work, and are founded on the
results of many experiments made on dry and
sound wood, grown in either Massachusetts, New
Hampshire, or Maine. The specimens were se-
lected as a just average of the respective kinds ;
and, as the experiments were carefully made, the
tables may be considered as reliable.

TIMBER-STRAINS.

TIMBER may be subjected to three kinds of
strain : —

IsZ, When the force tends to pull the piece in
the direction of its length : this is called tensile
strain.

2d, When the force tends to bend it in the direc-
tion of its depth, or across the fibres : this is com-
monly known as cross-strain.

3d, When it tends to compress it in the direction
of its length, or what is called compressive strain.

TENSILE STEAIN.

The following table exhibits the tensile strength
of an inch-square rod of each of the kinds of wood
in common use ; or, in other words, the power each

TIMBER-STRAINS. 45

will resist when so applied as to tend to tear it
asunder in the direction of its length : —

Kind of Wood. Weight in Pounds.

Black Spruce 10,260

White Pine 8,300

Carolina Pine 12,000

White Oak 13,200

Hemlock 9,100

Chestnut 10,500

PROBLEM I.

TO DETERMINE THE TENSILE STRENGTH OF A RECTANGULAR
TIMBER.

RULE. — Multiply the thickness of the piece in
inches by its depth * in inches, and the product by the
weight set against the kind of wood in the table. The
product so obtained will be the force in pounds the
piece will resist.

EXAMPLE. — What force will be required to pull
asunder a tie-beam of spruce, 7 inches thick and 10
inches deep?

Thickness, 7 10,260 Breaking-power.

Depth, 10 70

70 Ans. 718,200 Ibs.

* The distance across the top of the beam, when it is in a
horizontal position, is commonly called its thickness; and that
of the side, from the top to the tinder part, its depth.

46 TIMBER STRAINS.

PROBLEM II.

TO DETERMINE THE DIMENSIONS OF A PIECE OF TIMBER
THAT WILL RESIST A GIVEN STRAIN, ONE SIDE ONLY
BEING GIVEN.

RULE. — Multiply the sum set against the kind of
wood in the table by the given side in inches, and divide
the force to be resisted by this product. The quotient
will be the dimension, in inches, of the side required.

EXAMPLE. — What must be the depth of a beam of
white pine, 4 inches thick, to resist a strain of 232,400
pounds ?

8,300 Breaking-weight. 33,200) 232,400 (7 inches.

4 Thickness. 232,400

33,200 Ans. 4 by 7 inches.

The following table exhibits the tensile strength
of various kinds of wood, as given by the authors
named : —

Kind of Wood. SqYncMnms. Experimentalist.

English Oak ...... 19,800 ..... Bevan.

„ „ ...... 17,300 ..... Muschenbrock.

Beech ......... 22,000 ..... Bevan.

„ ......... 17,300 ..... Muschenbrock.

Ash .......... 16,700 ..... Bevan.

„ .......... 12,000 ..... Muschenbrock.

Elm .......... 14,400 ..... Bevan.

„ .......... 13,489 ..... Muschenbrock.

TIMBER-STRAINS. 4)7

Locust 16,000 Bevan.

„ 20,582 Muschenbrock.

Walnut 7,800 Bevan.

„ 8,130 Muschenbrock.

Poplar 7,200 Bevan.

„ 6,641 Muschenbrock.

Pitch-Pine 7,818 Muschenbrock.

Larch 8,900 Bevan.

Teak 8,200 Bevan.

Mahogany 21,800 Bevan.

Lancewood 23,400 Bevan.

The following corollaries, in relation to the
strength of timber, have been established by ex-
periment : —

1st, A piece of timber should not be subjected
to a permanent strain of more than a fourth of the
power that would break it.

2«/, A piece of perfect timber, while in a level
position and properly' supported, is supposed to be
of equal tensile strength throughout ; and, whether
the piece be long or short, it is liable to part in
one place nearly as quick as in another.

3d, A piece of perfect timber, in a vertical po-
sition, is in tensile strength proportionate to its
length ; a short piece being stronger, since a long
one must, in addition to the power applied to the

48 TIMBER-STRAINS.

lower end, sustain its own weight ; and hence,
when it breaks, will part near the top.

4th, In calculating the strength of any piece of
timber, only so much of the wood should be mea-
sured as is continued throughout the entire stick.
For instance, a tie-beam measuring eight by ten
inches, having an inch-and-a-half rod passing
through it, should be considered as measuring but
six inches and a half thick ; and if the ends of
struts, or any thing of the kind, be cut down, into
and across the top of the beam, two inches, it would
then measure but eight inches deep.

5th, A rectangular beam supported at both ends,
with its diagonal placed vertically, will thereby be
reduced, in cross-strength, one-tenth.

6th, The tough and hard woods, as oak and
chestnut, are about an eighth, and the soft ones, as
spruce, pine, and hemlock, from a sixteenth to a
twentieth, as strong, when the power is applied at
right angles to the fibres, as when applied to their
length. This power is that which a pin exerts on
the wood of a post through which it has been
driven, when the tenon, which is pinned in, tends
to drag it out, and thereby split the wood.

49

CROSS-STRAIN.

WHEN a piece of timber is supported only at the
ends, and a weight or power is applied at the
centre, it will, if the force is sufficient, bend or sag.
If the power of resistance be great, the wood is
said to be stiff ; but, if it bends easily, it is said to
be flexible. Should it bend much, without fracture,
it is called tough.

If a beam, two feet long and an inch square,
will support, at its centre, five hundred pounds,
one of the same length, two inches wide and an
inch deep, will support a thousand pounds. Hence
we have as a rule, that beams of the same depth are
to each other as their thickness. Should the beam
described be turned upon its side, so as to make it
an inch thick and two inches deep, it will support
two thousand pounds. "We therefore have as a
second rule, that beams of equal thickness are to
each other as the square of their depth.
4

50 CROSS-STRAIN.

If a beam, an inch square and two feet long,
will support, at its centre, five hundred pounds, one
four feet long will support but two hundred and
fifty pounds. A third rule, therefore, is, that learns
are to each other inversely as their length*

If a beam, sixteen feet long, supported at the
ends, will support, at its centre, a weight of eight
hundred pounds, it will support equally well twice
that amount if eight hundred pounds be placed at
points, each four feet from either side of the
centre, — half-way between the centre and the
points of support. Again : it will equally well
support twice that amount (or 3,200 pounds), if
sixteen hundred pounds be placed at points, each
half-way from those last named and the points
of support (two feet). A beam, therefore, that
will support a thousand pounds at its centre, will
support two thousand pounds if the weight be
distributed equally over its entire length.

A beam, having but one end fixed in a wall,
will sustain only a fourth as much weight, when
applied to the end, as will one of the same dimen-

* Experiments made by Bufibn tend to prove that the
strength of a beam does not decrease in exact geometrical
progression to its length, but that it will actually bear some-
thing more than half the amount which would break one of
half its length.

CROSS-STRAIN. 51

sions with both ends in like manner supported, and
the weight placed at the middle. When the weight
is equally distributed over the entire length of a
beam which has only one end supported, it will
sustain twice the amount that would break it if
applied to the middle.

Should three beams be fixed at one end in a
wall, and the other end left unsupported, — one
of them inclined upwards, one at the same angle
downwards, and the third level or at right angles
with the wall, — that inclined upwards would sus-
tain the least weight ; that inclined downwards, the
most ; and the horizontal one, a mean between
the two. In calculating the strength of an inclined
beam, the distance from the end of the beam, at
right angles with the wall, should be taken as the
actual length of the beam ; which length, as a
basis, will give the strength of the beam, if, instead
of being inclined, it were placed hi a horizontal
position.

From the foregoing data, it will be seen, that,
by the aid of tables and rules, it is easy to deter-
mine the strength of inclined as well as horizon-
tal timbers.

The following table exhibits the cross-strength
of each of the several kinds of wood ; the pieces

52 CROSS-STRAIN.

being dry, an inch square, and twelve inches long
between the points of support : —

Wood. Breaking-weight in Ibs.

Black Spruce 590

White Pine 548

Carolina Pine 684

White Oak 738

Hemlock 426

Chestnut . 595

PROBLEM III.

TO DETERMINE THE CROSS-STRENGTH OF A STICK OF
TIMBER.

RULE. — Multiply the thickness of the stick in
inches by the square of its depth in inches, and divide
the product by the length of the piece in feet. With
the quotient multiply the sum in the table that is set
against the kind of wood ; and the product will be the
breaking-weight in pounds.

EXAMPLE. — What weight will a spruce-beam, 18 feet
long, 6 inches thick, and 8 inches deep, sustain ?

Length.

Breaking-weight.

8 Depth.

18)384(21.3

590

8

36

21.3

64 Square.

24

177.0

6 Thickness.

18

590

1180

384

60

54

12,567.0 Ibs.

CROSS-STRAIN. 53

PROBLEM IV.

TO DETERMINE THE DEPTH OF A STICK OF TIMBER THAT
WILL SUSTAIN A GIVEN WEIGHT, THE THICKNESS AND
LENGTH BEIXG GIVEN.

RULE. — Divide the weight to be sustained by the
sum set against the kind of wood in the table. Mul-
tiply the quotient by the length of the stick in feet, and
divide the product by the thickness of the stick in
inches. The square-root of the quotient will be the
depth of the stick in inches.

EXAMPLE. — What depth will be required to a stick
of chestnut, 19 feet long and 3 inches thick, that it may
sustain 27,251 pounds?

Breaking-
weight. . . .

595)27251(45.8 45.8 290.066(5.38
2380 19 Length. 25

3451 4122 - 103) 400

2975 458 309

4760 Thickness 3) 870.2 1068) 9166
4760 8544

290.066

Ans. 5T3QS5 inches nearly.

54 CROSS-STRAIN.

PROBLEM V.

TO DETERMINE THE THICKNESS OF A STICK OF TIMBER
THAT WILL SUSTAIN A GIVEN WEIGHT, THE LENGTH
AND DEPTH BEING GIVEN.

RULE. — Divide the weight to be sustained by the
sum set against the kind of wood in the table. Multi-
ply the quotient by the length of the stick in feet, 'and
divide the product by the square of the depth in inches.
The quotient will be the thickness of the beam in
inches.

EXAMPLE. — What should be the thickness of a
hemlock-beam, 21 feet long and 12 inches deep, that it
may sustain a weight of 19,170 pounds?

Breaking-weight.

426)19170(45 45 12 Depth.

1704 21 Length. 12

2130 45 144 Square.

2130 90

144) 945 (£.56
864

810
720

900
864

Ans. 6I5J3_ inches nearly.

The following table exhibits the breaking-weight
of various kinds of wood as given by the authors
therein named : —

CROSS-STRAIN.

55

Experiments on the Strength of Woods.

END OP WOOD.

Length In Feet.

°

1

1

1

IDr flrctlon In
Incites in the
time of fracture.

Welpht in Pounds
that l.roke the
piece.

!

English Oak, young tree
Oak, old ship-timber . . .
,, from old tree ....
,, medium quality . .
Green Oik

2

2.5
2
2.5
2.5

1
1
1

1

1

1
1
1

187

1.5
1.38

482

264
218
284
219

Tredgold.
Ebbels.

Otk from Riga

2

1

1

1.25

357

Tredgold.

Green Oak

11.75

85

85

3.2

25S12

Buffon.

Beech, medium quality .
Alder

2.5
2.5

1
1

1
1

271
212

Ebbela.

Plane-tree

2.5
2.5

1
1

1

1

243
214

»

2.5

1

1

180

Ash, from young tree . .
\sh . . .

25
25

1
1

1

1

2.5

2.38

324
314

Tredgold.

Common Elm
Green Witch-Elm ....
,, Acacia
Sp. Mahogany, seasoned .
Hond. „ „
Green Walnut

25
2.5
2.5
25
2.5
2.5

1
1
1
1
1
1

1

1
1
1
1
1

116
192
249
170
255
195

Ebbe'ls.

Tredgold.
Ebbek

Lombardy Poplar ....
Abele Poplar
Teak

2.5
2.6

1

1
fl

1
1
?.

1.5
4.0

131
228
820

Tredgold.
Barlow.

Willow

•>5

1

1

30

146

Tred°'old

Birch . . . . -

25

1

1

2(>7

Ebbels.

Cedar of Libanfls, dry . .
Riga Fir

2.5
25

1
1

1
1

2.75
13

165
212

Tredgold.

MemelFir
Norway Fir. fr. Long Sd.
Mar-Forest Fir

2.5
2

1

1

9

1
1-

9,

115
1.125
55

218
396
360

»>
Barlow

Scotch Fir, Engl. growth

Christiania white Deal . .
American white Spruce .
Spruce-fir, British growth
American Pine, Weymouth
Larch, choice specimen .
,) medium quality .
„ yery young wood .
Ri°u Fir

25
2.5
2
2
2.5
2
2.5
2.5
•2:,
4

1

1
1
1
1
1
1
1
1
S

I
1
1
1
1
1
1
1
1
ft

1.75

0937
1.312

1125
3.0

1.75

233
157
343
285
186
329
253
223
129
4530

Tredgold.
Ebbels.
Tredgold.

Ebbels.
Tredgold.

Red Pine

4

3

3

3780

Yellow Pine .

4

^

ft

2756

Cowrie
Poona

4
, 4

IS
3

3

3

4110
3990

56 CROSS-STRAIN.

It has been decided by experiment, that a fifth
of the breaking-weight will cause deflection, in-
creasing with time, and ultimately producing a
permanent set. By an examination of the table,
it will be discovered that wood of old trees is much
weaker than that of those of mean age ; also that
timber is stronger as it is heavier, though the in-
crease in all examples is not exactly proportionate
to its solidity.

57

COMPRESSION.

COMPRESSION is the power exerted on a post when
loaded with a superincumbent weight, as that which
is exerted on the collar-beam, or struts and rafters
of a truss.

It has been discovered, that a timber, if placed
as a post, whether long or short, would in either
case, if entirely inflexible, support a weight equally
well. But, inasmuch as there is some flexibility
in aU timber, a piece will, if higher than about
seven times its diameter, bend and break before
it can be crushed by compression ; and it is stated,
that a piece, if a hundred times as high as it is
in diameter, will be incapable of supporting the
smallest weight*

The nature of the subject under consideration
makes it next to impossible to determine rules
which will be of much service. As the compres-

* Gwilt's " Encyclopaedia of Architecture," p. 442, art. 1600.

58 COMPRESSION.

sive strength of timber is so variable in different
specimens, and in none so geometrically propor-
tionate to its length as to give reliablfe data, rules
for ascertaining the exact size for all purposes and
situations would only confuse, if not deceive, the
mechanic.

The power of resistance to compression is so
great, that no serious danger need be apprehended
from the use of such dimensions of timber for
collar-beams, truss-rafters, struts, &c. (these being,
when in use, in a state of compression), as will
generally agree with the tie-beams and purlins ;
and the only rule that may be considered of value
is, that the compressed pieces of any work should
bear such a proportion to those subjected to a
tensile or cross strain as will make the whole truss,
whatever its design, comparatively uniform in ap-
pearance throughout.

The following table, prepared by Mr. Tredgold,
was designed to aid in determining the strength of
timber when compressed in the direction of its
length. The calculations were made for foreign
timber. It is presumed, however, they are quite
as reliable for timber grown in America as for that
grown in England, since in neither is their truth
susceptible of mathematical demonstration.

COMPRESSION. 59

Kind of Wood. Proportional Strength.

English Oak 0015

Beech 00195

Alder 0023

Green Chestnut 00267

Ash 00168

Elm 00184

Locust 00152

Riga Fir 0015,2

MemelFir 00133

Norway Spruce . . -. . . . .00142

White Pine .00157

Larch .0019

PROBLEM VI.

TO DETERMINE THE DIAMETER OF A ROUND COLUMN THAT
WILL SUPPORT A GIVEN WEIGHT.

RULE. — Multiply the weight in pounds by 1.7 times
the amount set against the land of wood in the table ;
then multiply the square-root of the product by the
length or height in feet ; and the square-root of the
last product will be the diameter of the post in inches.

If the column be shorter than ten times its
diameter, the dimensions ascertained by this rule
will be too small ; in which case, the true diameter
may be determined by Problem VIII.

60 COMPRESSION.

PROBLEM VII.

TO DETERMINE THE SIZE OF A RECTANGULAR POST THAT
WILL, SUPPORT A GIVEN WEIGHT.

RULE. — Multiply the weight in pounds by the
square of the length of the post in feet, and this
product+by the number set against the kind of wood
in the table. Divide the product by the breadth in
inches, and the cube-root of the quotient will be the
thickness in inches.

In case the post is less than ten diameters high,
the dimensions will be determined by Problem
VIII., as before directed.

RESISTANCE TO CRUSHING.

According to Rennie's experiments, the power
of wood to resist crushing (a cube an inch square
being used, and the power applied to the end of
the grain) is as follows*-: —

Kind of Wood. Resistance.

Elm 1284

American Pine 1606

White Deal 1928

English Oak 3860

COMPRESSION. 61

PROBLEM Vffl.

TO DETERMINE THE LOAD ANY POST OF LESS THAN TEN
TIMES ITS DIAMETEK IN HEIGHT WILL SUPPORT WITH-
OUT CRUSHING.

RULE. — Multiply the area of the post in inches by
the weight that will crush a square-inch of the kind
of wood. A fourth of the product is the greatest
permanent load the post will bear with safety.

Only two other strains to which wood may be
subjected need be noticed.

One is that exerted by the foot of a truss, rafter,
or any thing of the kind, on the wood between it
and the end of the tie-beam on which it stands ;
the tendency being to slide, or push off the wood.
The quality which resists this is called the lateral
adhesion. Experiments have proved that the soft
woods, as spruce, pine, &c., will resist a force
of from five to seven hundred pounds, and the
hard woods, as oak and chestnut, from six to nine
hundred pounds, to the square-inch. As no piece
of good carpentry would be dependent on the
simple adhesion of the wood alone for support,
but, where the thrust is one of more than ordinary
moment, bolts or straps should be employed, rules
and further suggestions are uncalled for.

62 COMPRESSION,

The other strain to which reference has been
made is where the power tends to tear asunder the
fibres of the wood in the direction of their length.
(See corollary 6, page 48.) Experiments made
on oak and chestnut show this resistance to be
from nineteen hundred and fifty to twenty-six
hundred pounds to the square-inch, and white pine
and spruce from six hundred and fifty to twelve
hundred pounds.

GEOMETRY AND SQUARE-ROOT.

65

GEOMETRY.

" GEOMETRY is the foundation of architecture, and
the root of mathematics." Such being the case,
a knowledge of its leading principles is essential
to a successful practice of the art of carpentry.
While only a part of the science is necessarily
called into requisition, that part is all-important.

It is presumed that every apprentice will make
himself familiar with the science by the study of
some good treatise on the subject. A few rules,
however, for making calculations will be given
in this work. They are introduced, as in other
cases of like nature, more for the purpose of
refreshing the memory than for imparting original
information.

The diagrams on Plate I. exhibit such general
principles as are most frequently used by the car-
penter ; and it is believed they will convey all the
information he may require.
5

66 GEOMETRY.

PLATE I.

FIG. 1. — To draw a line perpendicular to another
at a given point.

From the points A and C, equally distant from the
given point B, with the radius AC describe arcs in-
tersecting each other at D. From this point to B draw
the line DB, which will be the line required.

FIG. 2. — To draw a line perpendicular to another
at its extremity.

Let B represent the extremity of the line. From any
point above the line AB, as a centre, describe the arc
DBA. Draw AD from the point where the arc cuts the
line AB. Through the centre C, and from the point
where AD cuts the arc, draw the line DB, which will be
the line required.

FIG. 3. — To draw an equilateral triangle to any
given base.

Let AB represent the base. From the points A and

B, with the radius AB describe arcs cutting each other at

C. From C, draw the lines CA and CB, which produce
the triangle required.

FIG. 4. — To construct a square of any given di-
mensions.

Let AB represent the given side. From A and B, as
centres, describe the arcs AD and BC. From E, the
point of intersection, set off EC and ED equal to EF,

"

\

A'

Kig.G.

-I)

GEOMETRY. 67

which are one-half the line EA; then draw from the
points the figure CABD.

FIG. 5. — To describe a regular octagon, or figure
of eight equal sides, of a given dimension.

Let AD represent the diameter of the octagon. From
this, draw the figure ADBC; then draw the diagonals
AB and CD. With the radius AE, on the points ADBC,
describe arcs cutting the square. From the points of
intersection, draw diagonals, and the octagon is formed.

FIG. 6. — To draw a regular hexagon or triangle
within a given circle.

Apply the radius of the circle six times around the
circumference, as at AB ; and the line is a side of the
hexagon. Draw a line from the points AC, and the line
is the side of an equilateral triangle.

FIG. 7 exhibits a method for finding the centre of a
circle when an arc is given ; also for describing a seg-
ment of a given height.

Let AB represent the base, and dC the height. Pro-
duce the lines AC and CB. On the points A and B, with
a radius of more than half the line AC describe the arcs
ef and gh. On the point C, with the same radius, de-
scribe the arcs ij and kl. Through the points of inter-
section, draw the lines mn and no, cutting each other at
the point n ; which will be the centre required.

FIG. 8. — To inscribe in a circle a regular pentagon,
or figure of five equal sides.

Draw two lines, AB and CD, perpendicular to each
other. Divide the radius Ab into equal parts, as at a.

68 GEOMETRY.

On a as a centre, with the radius «C describe the arc
Cc ; then, on B as a centre, with the radius Be de-
scribe the arc cd, and from the point of intersection d
to C will be a side of the pentagon. A decagon, or
figure of ten sides, is described by drawing the lines fg
and gC, and then proceeding thus with each of the five
sides till the figure required is completed.

FIG. 9. — This figure exhibits a method of deter-
mining the dimensions and form of a rectangular
stick of timber cut from a round stick, ivhich shall
be capable of supporting the greatest weight when
lying in a horizontal position.

The circle represents the outline of the log or stick,
and ABDC the stick to be cut therefrom. To determine
which, divide the line AD (the diameter of the log) into
three equal parts. On the points e and f erect perpen-
diculars ; which produced, cut the circumference at the
points BC ; which, together with the points AD, give
the corners of the required stick.

FIG. 10. — To describe an elliptic arch by inter-
secting lines, the base and height being given.

Let AB represent the base, and AC the height. Di-
vide AC and BD into any number of equal parts ; then
divide CD into two equal parts, as at E. Divide CE
and DE each into the same number of parts as AC and
BD. Then, from the points described, draw lines as
shown in the figure ; and the points where these intersect
will be the track of the curve. Trace a line through
them, and we have the figure AEB.

GEOMETRY. 69

I

DEFINITIONS.

The diameter of a circle is a right line drawn through
its centre, and terminated at each end by the circumfe-
rence, as AB, fig. 8.

The radius of a circle is a right line drawn from the
centre to the circumference, being half the diameter ; as
C6, fig. 8.

An arc of a circle is any portion of the circumfe-
ference ; as DB, fig. 2.

A chord is a right line joining the extremities of an
arc ; as AB, fig. 7.

A segment is any part of a circle bounded by an arc ;
as ABC, fig. 6.

A semicircle is half a circle ; as ACB, fig. 8.

A sector is any part of a circle bounded by an arc and
the radii ; as pus, fig. 7.

A quadrant is a quarter of a circle ; as A6D, fig. 8.

70 GEOMETRY.

PROBLEM I.

TO FIND THE AKEA OF A PARALLELOGRAM, WHETHER IT
BE A SQUARE, A RECTANGLE, A RHOMBUS, OR A RHOM-
BOID.

RULE. — Multiply the length by the perpendicular
height, and the product will be the area.

PROBLEM II.

TO FIND THE AREA OF A TRIANGLE.

RULE. — Multiply the base by the perpendicular
height, and half the product will be the area.

PROBLEM III.

TO FIND THE AREA OF A TRIANGLE WHOSE THREE SIDES
ARE GIVEN.

RULE. — From the half-sum of the three sides sub-
tract each side severally. Multiply the half-sum and
the three remainders together, and the square-root
of the product will be the area required.

PROBLEM IV.

ANY TWO SIDES OF A RIGHT-ANGLED TRIANGLE BEING
GIVEN, TO FIND A THIRD SIDE.

CASE I. — When two sides are given, to find the hy-
pothenuse.

RULE. — Add the squares of the two legs together, and
the square-root of the sum will be the hypothenuse.

GEOMETRY. 71

CASE II. — The hypothenuse and one of the legs being
given, to find the other leg.

RULE. — From the square of the hypothenuse take
the square of the given leg, and the square-root of the
remainder will be equal to the other leg.

PROBLEM V.

TO FIND THE AREA OF ANY REGULAR POLYGON.

RULE. — Multiply half the perimeter of the figure
by the perpendicular falling from its centre upon one
of the sides, and the product will be the area of the
polygon.

PROBLEM VI.

TO FIND THE AREA OF A REGULAR POLYGON, WHEN THE
SIDE ONLY IS GIVEN.

RULE. — Multiply the square of the given side of
the polygon by that number which stands opposite to
its name in the following table, and the product will
be the area : —

No. of Sides. Names. Multiplier.

3 ... Trigon 0.43301

4 ... Tetragon 1.00000

5 ... Pentagon 1.72047

6 ... Hexagon 2.59807

7 ... Heptagon 3.63391

8 ... Octagon 4.82842

9 ... Nonagon 6.18182

10 ... Decagon 7.69420

11 ... Undecagon 9.36564

12 ... Duodecagon 11.19615

72 GEOMETRY.

As the foregoing table extends to five places
of decimals, it is exact enough for all practical
purposes.

PROBLEM VII.

THE DIAMETER OF A CIRCLE BEING GIVEN, TO FIND THE
CIRCUMFERENCE.

RULE. — Multiply the diameter by 22, and divide
the product by 1 : the quotient will be the circumfe-
rence. Or multiply the diameter by 3, and add a
seventh part of the diameter to the product : the sum
will be the circumference as obtained before. Either
of these methods is sufficiently correct for common
purposes.

PROBLEM VIII.

THE CIRCUMFERENCE OF A CIRCLE BEING GIVEN, TO FIND
THE DIAMETER.

RULE. — Multiply the circumference by 7, and divide
the product by 22 : the quotient will be the diameter.

PR.OBLEM IX.

THE CHORD AND HEIGHT OF A SEGMENT BEING GIVEN, TO
FIND THE RADIUS OF THE CIRCLE.

RULE. — To the square of the half-chord add the
square of the height, and divide the sum by twice
the height of the segment : the quotient will be the ra-
dius of the circle when it is less than a semicircle.

GEOMETRY. 73

PROBLEM X.

TO FIND THE AREA OF A CIRCLE, THE DIAMETER BEING
GIVEN.

RULE. — Multiply half the circumference by half
the diameter, and the product will be the area.

PROBLEM XI.

TO FIND THE AREA OF A SECTOR OF A CIRCLE.

RULE. — Multiply the radius, or half the diameter,
by half the length of the arc of the sector; and the
product will be the area.

PROBLEM XII.

TO FIND THE AREA OF THE SEGMENT OF A CIRCLE, THE
CHORD AND HEIGHT OF THE ARC BEING GIVEN.

RULE. — To two-thirds of the product of the base,
multiplied by the height, add the cube of the height
divided by twice the length of the segment ; and the
sum will be nearly the area.

PROBLEM

TO FIND THE AREA OF AN ELLIPSIS, THE TRANSVERSE AND
CONJUGATE, OR LONG AND SHORT, DIAMETERS BEING
GIVEN.

RULE. — Multiply the transverse axis by the conju-
gate, and the product multiplied by .7854 will be the
area.

74 GEOMETRY.

PROBLEM XIV.

TO FIND THE AREA OF A PRISM.

RULE. — Multiply the area of the base, or end, by
the perpendicular height; and the product will be the
solidity.

PROBLEM XV.

TO FIND THE SOLIDITY OF A PYRAMID.

RULE. — Multiply the area of the base, or end, by
the perpendicular height; and a third of the product
will be the solidity.

PROBLEM XVI.

TO FIND THE SOLIDITY OF THE FRUSTUM OF A SQUARE
PYRAMID.

RULE. — To the rectangle of the sides of the two
ends add the sum of their squares. That sum being
multiplied by the height, a third of the product will be
the solidity.

PROBLEM XVn.

TO FIND THE SOLIDITY OF A SPHERE, OR GLOBE.

RULE. — Multiply the cube of the diameter by .5236,
and the product will be the solidity.

GEOMETRY. 10

PROBLEM XVIU.

TO FIND THE SOLIDITY OF THE SEGMENT OF A GLOBE.

RULE. — To three times the square of half the dia-
meter of the base of the segment add the square of
the height of the same. Multiply that sum by the
height named, and the product multiplied by .5236
will give the solidity.

PROBLEM XIX.

TO FIND THE CONVEX SUPERFICE OF A RIGHT CYLINDER,
THE CIRCUMFERENCE AND LENGTH BEING GIVES.

RULE. — Multiply the circumference by the length,
and the product will be the area.

PROBLEM XX.

TO FIND THE CONVEX SUPERFICE OF A RIGHT CONE, THE
CIRCUMFERENCE AND SLANT SIDE BEING GIVEN.

RULE. — Multiply the circumference by the slant
side, and half the product will be the area.

PROBLEM XXI.

TO FIND THE CONVEX SUPERFICE OF THE FRUSTUM OF A
CONE, THE CIRCUMFERENCES OF BOTH ENDS AND THE
SLANT SIDE BEING GIVEN.

RULE. — Multiply the sum of the circumferences by
the slant side, and half the product will be the area.

76 GEOMETRY.

PROBLEM XXII.

TO FIND THE SUPERFICE OF A SPHERE, OB GLOBE, THE
CIRCUMFERENCE BEING GIVEN.

RULE. — Multiply the square of the circumference
by .3183, and the product will be the super/ice.

PKOBLEM XXIII.

TO FIND THE CONVEX SUPERFICE OF THE SEGMENT OF A
GLOBE, THE DIAMETER OF THE BASE OF THE SEGMENT
AND ITS HEIGHT BEING GIVEN.

RULE. — To the square of the diameter of the base
add the square of twice the height, and the sum mul-
tiplied by .7854 will give the superjice.

PROBLEM XXIV.

TO FIND THE CONVEX SUPERFICE OF AN ANNULUS, OR RING,
WHOSE THICKNESS AND INNER DIAMETER ARE GIVEN.

RULE. — To the thickness of the ring add the inner
diameter. Multiply the sum by the thickness, and the
product multiplied by 9.869 will be the superjice.

77

SQUARE-ROOT.

As the extraction of the square-root of numbers is
required to calculate the strength of timber, the
rule will be given below, more to refresh the me-
mory than to give original information as to its
principles ; it being presumed that every intelligent
workman has made himself familiar with the rules
of common arithmetic through works especially
designed for the purpose.

RULE. — 1st, Separate the given number into periods
of two figures each, by placing a point over the first
figure at the right hand, and then over every other
figure towards the left.

2d, Ascertain the greatest square-number contained
in the left-hand period, and place the root of it at the
right hand of the given number, after the manner of a
quotient in division. Subtract the square of this root
from the period named, and to the remainder bring
down the next period for a new dividend.

3d, Double the quotient already found, and place it
at the left of the dividend for a divisor. Find how

78 SQUARE-ROOT.

many times this divisor is contained in the new divi-
dend (omitting the right-hand figure), and place the
figure in the root as the second figure of the same,
and likewise on the right hand of the divisor. Multi-
ply the divisor by the last quotient-figure, subtract the
product from the dividend, and to the remainder bring
down the next period for a new dividend.

4th, Double the quotient already found for a partial
divisor, and from these find the next figure in the root
as before directed : so continue the operation until all
the periods have been employed. Should a remainder
exist, add two ciphers as a new period, and so continue
pointing off the root after the rules of decimal frac-
tions.

EXAMPLE. — What is the^ square-root of 59,325 ?

59325 (243.5
4

44)193
176

483) 1725

1449

4865) 27600
24325

Required the square-root of 326,041 : —

326041(571
25

107) 760
749

1141) Till"
1141

EQUILIBRIUM

STRAINS ON TIMBER.

81

EQUILIBRIUM OF STRAINS ON
TIMBER.

A KNOWLEDGE of the relation that one part of a
frame sustains to each of the others is of great
importance to the carpenter ; for, if ignorant of
the force that each piece will be required to exert
or resist, he cannot determine beforehand whether
the assemblage will possess sufficient strength to
answer the purpose designed. The timbers of a
frame are usually acted upon by direct, and also
by complex, forces.

POSITION.

The strains to which the timbers of a structure
are subjected will always be governed by their
position ; and their particular inclination will in-
crease or diminish these strains in accordance with
the laws of mechanical forces.

6

82 EQUILIBRIUM OP STRAINS.

PLATE H.

To the side of a beam, as shown at Fig. 1, Plate II.,
affix two pulleys, A and B. To the ends of a string
passing over each, attach weights, as C and D. At some
point of the string between the pulleys, as E, tie
another; to the end of which affix weight F, which
must be lighter than the sum of the weights C and D.

If the work be then left to itself, the point E will
assume a certain position, and the whole will remain at
rest; and, if the arrangement be disturbed by pulling
down or lifting up either of the weights, each part will
recover its original position when left free.

It is thereby proved, that, when in that position alone,
the parts are in equilibria. If the position of the
strings, when the weights are thus balanced, be drawn
on paper, and any portion of the line Ei be divided into
a scale of parts representing the number of pounds in
the weight F, the line AE be continued to h, and the
line ik be drawn parallel to EB, then iTi, measured 'by
the scale, would show the number of pounds weight at
D ; and the line E^, measured in the same manner, the
number of pounds in the weight C : or, in other words,
the three sides of the triangle 'EM will be respectively
proportionate to the three weights. Therefore, to ascer-
tain to which weight either side corresponds, we have but
to find which weight draws in the direction of that par-
ticular side.

As a deduction of the foregoing, we have the follow-
ing rule : If a body be kept at rest by three forces, two

STRAINS 03f TDIBEP.

pi.n

EQUILIBRIUM OF STRAINS. 83

of which are represented in magnitude and direction
by two sides of a triangle, the third side will represent
the magnitude and direction of the other force.

NOTE. — Before proceeding to the immediate consideration
of the strains to which timbers in a frame may be subjected,
the student should make himself familiar with the mechanical
principles demonstrated by Fig. 1, Plate II., as the principles
therein contained are the base on which rests the science of
carpentry.

We will now suppose that the point E, in Fig. 1, — in-
stead of being sustained by the weights C and D, which
act in the direction Ea and E6, as shown at Fig. 2, — is
supported by timbers HE and JE. The weight F being
suspended from the point E, the timber HE will sustain
a force equal to that which is exerted in the direction
of E6 ; and JE, a force equal to that exerted in the di-
rection of Ea.

To determine these forces, we proceed as follows : Let
any portion of the line EF, as EG, represent the weight
F. Draw op parallel to HE ; and op, measured by the
scale, will represent the weight sustained by HE, and oq
that sustained by JE.

From the above data we deduce the following : —

1st, A force or power applied to the end of a timber
always acts in the direction of its length.

Id, If a post be somewhat inclined, as AC, Fig. 3,
and another timber put against it, as BC, the post will be
relieved of a part of the strain ; for each piece will sup-
port a weight proportional to its own inclination.

3d, Should a weight be applied to the apex of two
pieces of like inclination, as at Fig. 4, it will exert an
equal strain on each.

84 EQUILIBRIUM OF STRAINS.

4th, A weight, applied as shown in Figs. 3 and 4,
tends to spread the timbers apart at the lower ends. In
Fig. 3, we have supposed them to rest against an im-
movable abutment. It is obvious, that, the strain being
a direct thrust, a tie connecting A and B will be an
equivalent to the abutments. Fig. 4 represents this, AB
being the tie-beam.

5th, If an inclined timber, as AB, Fig. 8, be cut at
the ends so as to rest level on the walls, it will have no
tendency to slide ; and therefore, so long as it remains in
this position, will not exert the slightest thrust on the
walls.

TO DETERMINE THE STRAINS EXERTED ON TIMBER.

Being in possession of the foregoing facts and deduc-
tions, the carpenter is enabled to determine the exact
strain to which the parts of any piece of framing will be
subjected.

Suppose it be required to determine the strain exerted
on each of the pieces shown at Fig. 3. From the point
where the pieces meet, draw the vertical line ab of any
convenient length ; from 6, draw cb parallel to AC. As-
suming the weight C to be five hundred pounds, we pro-
ceed as follows : —

Let the line ab represent the weight. Divide it into
ten equal parts, and one of these again into ten others.
Each one of the divisions last named — being a hundredth
part of the line «6, which represents the whole weight
of five hundred pounds — will represent five pounds.
Measure the line cb by this scale ; and as many parts as
it contains, n^iltiplied by five, will be the number of

EQUILIBRIUM OF STRAINS. 85

pounds the piece AC must support. Proceed in the
same way with ca, and the result will be the weight
supported by BC.*

The horizontal strain exerted on the tie-beam may be
determined as follows : From the point c, Fig. 4, draw a
line parallel to the tie-beam. The line cd, measured by
the scale as before described, will represent the pressure,
or strain, exerted thereon by each piece. If the pieces
be unequally inclined, as in Fig. 3, proceed as before
described ; and the parallel lines will represent the hori-
zontal strain, as in Fig. 4. af will represent the vertical
strain on A ; and ad, the strain on B.

If a weight be applied to any part of an inclined
beam, as W, Fig. 8, the direct transverse strain may be
determined on the same principles. From a point be-
neath the centre of the weight, draw the line ab of any
convenient length. From the end of the line at b, draw
cb at right angles with the beam. Having divided the
line ab into a scale of parts representing the number
of pounds weight at \V, we have, by measuring the line
cb with this scale, the number of pounds weight exerted
as transverse or cross strain on the beam AB.

It may also be observed, that ac will give the force
with which the ball would move down the beam ; or, in
other words, if the ball be fixed, it would show the force
exerted in the direction of the beam, dc will represent
the strain exerted on the wall, should the beam rest
against it. Those strains to which the several timbers of

* It should be borne in mind, that the particular inclination
of the pieces determines the aggregate pressure; and, although
the sum of the two may amount to more than the weight ap-
plied, it does not necessarily follow that the calculation is
wrong.

86 EQUILIBRIUM OF STRAINS.

a crane are subjected are identical with those exerted on
the various timbers of most examples of framing.

While the crane is an exceedingly simple machine, it
fully illustrates every point under consideration ; and has,
in consequence, become with most authors a favorite
model for illustration.

Fig. 5 illustrates the nature and amount of strain a
weight will exert on both a tie and a strut at the same
time. Instead of the beams HE and JE of Fig. 2, as
substitutes for the ropes AE and BE of Fig. 1, we may
substitute, in place of rope EB, the strut CE, Fig. 5,
and permit a rope AE to remain. The weight is sup-
ported in this example precisely as it was in each of the
others, and the method of procedure to ascertain the re-
spective strains is the same. EG, as a scale representing
the weight, is the scale for measuring po, which is the
strain on the strut CE ; and os, the strain on the tie, or
rope.

Fig. 6 represents the same principle, and, in like
manner, illustrates the means of determining the strain
on inclined timbers. Ab represents the scale of weight.
The line Ac, measured by the scale, will give the strain
on AB ; and be, that on CA. Should the projecting tim-
bers be inclined downwards, the method of calculation
would be the same.

If a beam be inclined against a wall, as at Fig. 7, and
the inclination be less than forty-five degrees, there will
be a tendency to slide ; but there is an angle to which
the end of the beam may be cut, so that this tendency
will be entirely overcome.

This discovery is of great value to the carpenter, since
the ends of truss-rafters, struts, &c., formed in accord-
ance with the rule, will exert no lateral strain on the
wood against ^which it abuts.

EQUILIBRIUM OF STRAINS. 87

From the centre of the beam at d, draw the line ab
parallel to AC. From a, draw of to the centre of the
beam at f; then, from a, draw ag to the centre of the
inclined beam at the lower end. ag will represent
the direction in which the beam presses upon the abut-
ment at B or g ; and the parts should therefore be cut
at right angles to the line named.

If we divide the line ab into a scale representing the
weight on the centre of the beam, and draw be perpen-
dicular thereto, be will represent the pressure against the
abutment, or the tensile strain exerted on the beam AB.

The foregoing comprehends all the important
principles relative to the strains exerted on the
timbers of a frame. In calculating these, however,
it is to be remembered, that the simpler a piece
of framing is, so is the resolution of the forces
exerted upon it; and vice versa. Although, in
most instances, strains are more or less complicated,
interfering with, and at times counteracting, each
other, still the exact strain upon each part is sus-
ceptible of calculation ; and any one who has suffi-
cient curiosity and perseverance may, by following
the rules, determine the nature and quantity of
the strain exerted on any specimen of framing,
however complicated.

SCARFING, FLOORS, AND
TRUSSED BEAMS.

91

SCARFING.

IT frequently occurs in the practice of carpentry,
that single lengths of timber are too short for the
distance required; in which case, the carpenter
unites two or more pieces by a process technically
termed SCARFING. The principal end to be at-
tained is, that, when put together, the scarfed stick
shall be equal in strength to a single piece of the
same dimensions. To attain this, it is necessary
so nicely to adjust the indentations, that the entire
surface of each part shall come in contact with
the corresponding part in the other piece ; so that
all may have a direct and uniform bearing, and
none be made to resist a force that should be
resisted by another.

Methods of scarfing are various ; and, of many,
we may truly say, that their design savors more of
the imagination of the artist than the sober expe-
rience of the mechanic.

92 SCARFING.

As it is not the purpose of this work to illustrate
the whole range of experiments in these things,
such methods only will be given as have proved
themselves most useful, presuming these will meet
every reasonable demand ; remarking merely, that,
when more complicated forms of indentation are
made, it is always at the expense of utility.

Beams are seldom exposed to more than two
kinds of strain which act upon the scarfing. One
is, when the power is so applied as to exert a strain
in the direction of the beam's length, as that pro-
duced by truss-rafters on a tie-beam : the other is,
when the force or power tends to sag or break the
beam in the direction of its depth.

In consideration of which, attention should be
paid, in the selection of a method of scarfing, to the
particular kind of strain to which the beam is most
liable to be subjected.

The parts of a piece of scarfing are held together
by bolts passing through the stick, as shown in
the plate ; and oak-keys are frequently put into the
scarf to prevent the parts sliding past each other,
as seen at a. Figs. 1, 2, 3. Care should be taken
that neither bolts nor keys be so large as to require
the removal of such an amount of wood as will
materially weaken the timber.

SCARFING. 93

These keys should be made of perfectly sound
dry white oak. They should be in two parts, each
slightly tapering on one side, so that, when driven
in, they may tighten the joint.

The iron straps or bars used on a scarf (as
shown on some of the examples) should be of the
best wrought iron, from a fourth to a half inch in
thickness, and from two to three inches wide, ac-
cording to the size of the beam scarfed ; and should
be four in number to each scarf. The length of the
scarfing for any beam should be about six times the
depth of the stick, and the bolts which confine
the work together should be from a half to three-
fourths of an inch in diameter ; making five-eighths
of an inch as the best average size for bolts to
beams of any dimension above eight or nine inches
square.

94 SCARFING.

PLATE III.

Plate III. exhibits five specimens, or examples, of scarf-
ing. Figs. 1, 3, and 5 are best adapted to resist a strain
in the direction of the length of the beam ; and Figs. 1,
2, and 4, to resist one in the direction of its depth. In
Figs. 4 and 5, the pieces are too short to admit of either
of the other methods. The planks of example at Fig. 5
should be of good dry white oak ; and, if the work is well
done, this scarf is equal in strength to either of the more
complicated methods. This practice is called by carpen-
ters "fishing a beam."

It is well to observe here, that the examples cited as
being particularly adapted to resist a longitudinal strain
are also capable of sufficiently resisting a vertical one.

SCARFING

Pl.Ul

i i T r i

i i

"T^-il

-^ 4-

I i !

I I

Tig. 5.

T T

95

FLOORS.

THE construction of floors is a branch of carpentry
which does not demand much scientific considera-
tion. If the timber be of proper size, sufficient in
quantity, and the work well done, all is accom-
plished that can be desired. To effect this, how-
ever, the carpenter should avail himself of such
rules as experience has proved to be valuable. The
timbers of a floor should be selected of proper size
to support any weight that will probably be placed
upon them. A warehouse-floor, for instance, may
at times be subjected to great strains, and should
therefore be heavily timbered. It is often the
practice, in constructing floors of the kind, to use
long floor-joists extending from eighteen to twenty-
four feet; in which case, the timbers vary in di-
mensions from three by thirteen inches to five by
fourteen inches, and they are usually placed from
fifteen to twenty inches apart from centres. A

96 FLOORS.

church or hall floor, when covered with people in
a standing position, packed close, is loaded a hun-
dred and twenty-five pounds to each square foot.
Timbers three by twelve inches, if the bearings are
not more than ten feet apart, placed sixteen inches
from centres, will sustain the weight; and these
dimensions are generally used in buildings of the
kind.

The floors of dwelling-houses may be lighter.
If the joists are materially longer, the size should
not be much decreased. The lengths being from
nine to fifteen feet, two by twelve will answer the
purpose : two by ten inch joists, and even two by
eight inch, are frequently used in cheap buildings.
The principal objection to light timber arises, not
from its liability to break, but from its vibration,
which is apt to crack the plaster of the ceiling
below.

FLOORS

n.r

.._

Ffe.4.

: -, : ' . .

Cmith . Knight * Tappan.Eng'

FLOORS. 07

PLATE IV.

The method of framing shown at Fig. 1 of this plate,
is, all things considered, quite as good as any in use.
More complicated methods are not often attended with
proportionate advantage. Fig. 2 exhibits the side of
the joists of the same floor, the girder, &c., all of which
will be readily understood without further explanation.

Fig. 3 exhibits a section of what is called a bridged
floor. It is, in principle, like the other, with the addi-
tion of the smaller joists which bridge over the principal
ones. Floors of this kind are seldom built in this coun-
try, but are much used in Europe.
, Fig. 4 exhibits a side-view, or section, of the floor
last described ; BB showing the ends of the principal,
and C the side of the bridging, joists. The part of
the diagrams at A illustrates the method of framing the
joists into the girder; the figures thereon denoting
the dimensions of each part, being calculated for a stick
twelve inches deep.

Even- floor should be well bridged. This may be
done in either of two ways : first, by cutting in between
the sides of the joists, and at right angles to them,
pieces of the same thickness and width as the joists
themselves; secondly, by cutting in pieces of board one
inch thick and three inches wide, crossing each other dia-
gonally, as seen at a, Fig. 1, Plate IV. The ends of
these pieces are scarfed, or cut bevelling, and firmly
nailed to the sides of the joists.

98

TRUSSED BEAMS.

IT frequently happens that beams are required to
support a great weight, while they extend across
a wide space, and can have no support from be-
neath. In such cases, it is necessary to truss the
work.

PLATE V.

Fig. 1, Plate V., exhibits a method of trussing a beam
by the use of an iron rod. All trussed beams are com-
posed of two pieces. In the example at Fig. 1, the
pieces are placed an inch apart, and the rod so bent as to
take the sag of the beam at the points aa. A bolt, an
inch in diameter, passes through the beam, and rests
on the truss-rod. At bb are iron plates, through which
the ends of the rod pass. This method may be employed
where the span is from twenty-five to thirty-five feet. If
the work is well done, the girder is strong ; but the ex-
pansion and contraction of the rod subject the work to
variation as the rod becomes longer or shorter.

- Ls

i-Eiagfet & Tampan. EngT?

TRUSSED BEAMS. 99

Figs. 3 and 4 are examples where oak-pieces and cast-
iron keys are used instead of a rod. The oak-parts
should be two by four inches, and let into the wood a
quarter of an inch on each side, leaving the beams an inch
and a half apart. The keys should be made with a
screw and nut at c to tighten the work. The abutments
at dd should also be of cast iron, and let into the wood,
like the oak.

Fig. 2 represents a beam built with oak-keys, two
inches square, let half an inch into the pieces, and the
whole bolted together. This method produces a very
strong beam, and is of great value. It is often the prac-
tice in carpentry to bolt two pieces of spruce together,
with an oak-board an inch thick between them. The
bolts should be of wrought iron, and five-eighths of an
inch in diameter. Should unusual strength be required,
the beam may be built with three or even four pieces,
with the truss-work between them, and the whole bolted
together as in an ordinary beam.

ROOFS, PARTITIONS, AND DOMES.

103

E 0 O F S.

tt THERE is no article," says the learned Ware, " in
the whole compass of the architect's employment,
that is more important, or more worthy of distinct
consideration, than the roof; and there is this satis-
faction for the mind of the man of genius in that
profession, that there is no part in which is greater
room for improvement."

The suggestions above quoted, although made
in the year 1756, remained quite unheeded till
near the close of the last century, when Mr. Peter
Nicholson made public the germ of an invention,
which has, in process of time, brought about as great
a revolution in the art of carpentry as the introduc-
tion of the arch did in that of masonry. The lead-
ing feature of the invention is the substitution of
iron rods for wooden king and queen posts. The
design by Mr. Nicholson was published in 1797;
but, as late as 1828, Mr. Tredgold says, in his ex-

104 ROOFS.

cellent Treatise on Carpentry, " It has been proposed
to let the ends of the principal rafters abut against
each other, and to suspend the king-posts by straps
of iron ; but a piece of good carpentry should de-
pend as little on straps as possible." From the tenor
of his remarks, it is reasonable to suppose that few,
if any, successful experiments had been made ; for
he afterwards refers the reader to a design in his
work, where the rafters abut against each other,
and the beam is suspended by planks bolted to their
sides. "This method," he adds, "is perhaps the
best in use." A valuable standard work, entitled
" Treatise on Architecture, Building, &c.," was pub-
lished in Edinburgh in 1844. On page 154 of
the work, attention is called to the suggestion of Mr.
Nicholson, made forty-seven years before. The
writer (Dr. Thomas Young) says, " There is a very
ingenious project offered to the public by Mr.
Nicholson (' Carpenter's Assistant,' p. 68). He
proposes iron rods for king-posts, queen-posts, and
all other situations where beams perform the office
of ties. . . . "We abound in iron ; but we must
send abroad for building-timber. This is, therefore,
a valuable project. At the same time, however, let
us not overrate its value." From the foregoing, it
appears, that, up to a late day, but little advance had

ROOFS. 105

been made ; the old methods of construction being
looked upon with more favor than the new.

At what time, or by whom, the idea was first
practically carried out in this country, is uncertain.
The burden of evidence, however, indicates, that,
although first published by Mr. Asher Benjamin,
he was indebted for the suggestion to Mr. Charles
G. Hall, now of Roxbury, Mass. Mr. Hall, an
Englishman by birth, and an able architect and
engineer, arrived in America in 1823. He soon be-
came associated in business with an eminent archi-
tect of that day, Mr. Alexander Parris. Under the
direction of these gentlemen, many large and im-
portant buildings were erected, in the roofs of most,
if not all, of which, the principle under considera-
tion was employed. Being thus freely used, it soon
commended itself to the judgment of other archi-
tects, who in turn adopted it ; and the work of Mr.
Benjamin was no sooner published than a reform
commenced, which has steadily advanced, until its
great value and economy are universally acknow-
ledged.

On the plates of this work pertaining to roofs
are designs calculated for various spans, and of such
rise, or pitch, as will accommodate them to any style
of building; each having been so designed that

106 ROOFS.

timber may be used of such dimensions as will
properly support a covering of heavy slates.

Of the inclination, or pitch, of the several roofs,
but little need be said, since designs for buildings
are so varied, that an attempt to illustrate them all
would- only encumber the work. A few suggestions
will be made, which, together with those amendments
naturally presenting themselves in particular cases,
will give all the information required.

The pitch of any roof, covered with shingles or
slates, should never be less than one-fourth the
width of the entire span ; for, if it be less, rain and
snow will, in severe storms, be driven through the
crevices. If the design of the building demands
less inclination, a covering of tin, copper, lead, or
something of like nature, should be used ; in which
case, any rise above a twenty-fourth of the whole
span will be all that is required. The extent of
the span will, however, to a certain degree, govern
the inclination and form of the roof, in order to
give strength to the truss. If the span is great,
and a low roof is desired, it is best to truncate it,
as shown on Plate IX., Fig. 1. Where slating is
used, the boards should be matched, and planed to a
uniform thickness ; for if the joints are left open,
as may be allowed in shingling, the passage of air

ROOFS. 107

through the openings carries with it rain or dry
snow, when, in ordinary storms, it would exhibit no
sign of defect.

TIMBERS OF A ROOF.

A trussed roof employs the following timbers, —
tie-beams, principal rafters, collar-beams, struts,
purlines, and common rafters.

TIE-BEAMS are the large and long timbers which
lie in a horizontal position, and extend across the
building at the base of the roof. They are usually
subjected to two kinds of strain. One is that which
is exerted by the principal rafters : the other is the
cross-strain, and may be produced by the weight
of the ceiling below, or a load upon the beams
themselves. In mortising tie-beams, as little wood
should be removed as the nature of the case will
allow. Tenons may be small, their use being simply
to retain each piece in its proper place. If the
figuring laid down in this work is followed, the tie-
beams of each design will be of sufficient size to
resist the strains exerted by the inclined parts, and
the rods will resist the cross-strain.

The weakest part of a tie-beam, and hence the

108 ROOFS.

one demanding most attention, is at its ends about
the foot of the rafters. To strengthen this part, it
is the usual practice to bolt pieces of strong white
oak or Carolina pine to the under side of the
beam. The pieces should be as thick as half
the depth of the beam, and of sufficient length to
extend from the end thereof to three feet beyond
the heel of the rafters. (See S, Fig. 2, Plate VI.)
Objections to the use of strengthening-pieces have
been made, because they present a joint or seam
where dampness may gather, and produce decay in
the wood ; also because they are in effect a camber
to the beam, exerting a thrust on the walls of the
building. To a certain extent, these objections are
valid ; but neither is of sufficient moment to out-
weigh the benefit produced. The objection first
named may be entirely obviated by thoroughly
painting the pieces when the work is put together.
The practice of cambering a tie-beam, by tightening
the rods till the beam is curved upwards, cannot be
considered advisable; for, if sufficient camber is
produced to give the beam additional strength by
its partaking of the nature of an arch, this is more
than counteracted by injury to the walls of the build-
ing. A large ceiling, if entirely level, presents an
optical delusion, leading the beholder to believe

ROOFS. 109

that the surface has a sag, or downward curve. In
furring such ceilings, a rise of an inch in twenty
feet will obviate the difficulty. While the carpenter
is cautious in cambering beams for either of the
purposes named, or any of like nature, he should
remember that there will be a settlement from the
shrinkage of the timbers, till each part has found
a solid bearing. Hence the rods should be kept
tightened ; and, when the work is completed, the
centre of the beam should be slightly curved upwards,
that the tendency named may be counteracted.

PRINCIPAL RAFTERS are the large inclined
timbers which support the purlins : they should
be of the same thickness as the tie-beam, and about
four-fifths as deep. To a beam seven by ten inches,
the rafter would be seven by eight inches. In some
examples of framing, as that shown on Plate XL,
Fig. 1 , one rafter is placed above another ; in which
case, both should be of the same size, having pieces
of oak-board, an inch and five-eighths thick and
four inches wide, let into each rafter five-eighths of
an inch, leaving the rafters three-eighths of an inch
apart for the passage of air between them : the pieces
should be perfectly dry, and tightly driven into the
grooves. The timbers should be bolted together
with bolts five-eighths of an inch in diameter.

110 ROOFS.

COLLAR-BEAMS are the horizontal timbers which
lie between the heads of principal rafters. They are
also known as straining-beams. As their use is
to prevent the rafters approaching each other, their
dimensions may be the same as the timbers named.
In designs where these beams are liable to sag, they
should be supported with struts, as seen at A, Plate
VIII. The case not unfrequently occurs where col-
lar-beams are serviceable as tie-beams, and thereby
strengthen the principal tie-beam : an example of
this kind may be seen at B and C, Plate XI. In
cases of this kind, separate rods will be required.
The top-truss, being needed as a truss, will require
rods of its own to make it complete in itself; the
main-beam being suspended by other rods.

STRUTS are the inclined pieces which support the
principal rafters. The ends of struts should always
be framed with a shoulder an inch and a half wide,
and sloping from this to the end of the piece. It
may be remarked here, that the ends of all braces
(whatever their position) should be formed with a
shoulder of like nature, proportional to the size of
the piece. Struts, being always in a state of com-
pression, need not be pinned to the beam or piece
they support, a short tenon being all that is required
to keep the parts in their proper place. The width

ROOFS. Ill

of struts should be the thickness of the principal raf-
ter ; and they should be about half as thick as the
rafter is deep. The carpenter should make it an
invariable rule to place the curved or cambered
side of a timber upwards, whenever such cambered
side exists.

PURLINS are the horizontal timbers extending
from truss to truss to support the common rafters.
They should always be framed or bridged over the
principal rafters, by notching into the back of
them and breast of the purlins, each half an inch,
making an inch when the work has been put to-
gether. Their size is determined by their length
of bearing and distance apart. "When the trusses
are within ten feet from centres, and the purlins
less than eight feet apart on the principal rafters,
they may be ,to them in thickness and depth,
respectively, as five to eight. They should not
be cut into lengths which will reach only over
single spaces, but continued whole ; and, when
they are put on, they should be made to break
joints, by the use of short lengths at the end of
every other one. It is to be remembered, that the
joints should always be made over the principal
rafter. In cases where the roof is large, and ex-
posed to the direct action of heavy storms, the

112 ROOFS.

purlins should be braced, like the posts and girts
of a side-wall.

COMMON RAFTERS are the outside timbers of a
roof, and are used simply to support the boarding.
Being uniformly loaded, only light pieces are re-
quired ; but they should always be jointed over the
purlins, and never placed more than eighteen or
twenty inches apart from centres. If the bearing
is not more than eight feet, they may be two by
six inches ; but, where it is more, their depth
should be proportionally increased. They should
be notched into a half-inch, to keep them from
sliding off the purlin ; but the purlin itself should
remain entire.

IRON WORK.

The bolts used at the foot of principal rafters
should not be less than five-eighths of an inch in
diameter, nor more than an inch. For most pur-
poses, three-fourths of an inch is best ; and, when
one of an inch in diameter is not sufficiently strong,
it is better to increase the number than the size,
and they should always be set at right angles with
the rafters. The rods which support the beams

ROOFS. 113

must be of sufficient size to prevent vibration, but
may vary in diameter according to the nature of
the work, from five-eighths of an inch to two inches
in diameter.

Great cafe should be exercised in the selection,
using none but the very best material.

It is a common practice, in some instances, to use
cast-iron boxings at the ends of principal rafters,
and such other parts of a truss as will be subjected
to great pressure, causing the fibres of the wood to
indent each other. It is rare, however, that box-
ings are absolutely necessary.

Where a piece of framing is liable to be exposed
to dampness before the work is put together, the
iron should be heated to a blue heat, and well oiled
over with the best quality of raw linseed oil. If
this is properly done, the pores of the iron will be
filled, and the metal effectually protected against
corrosion.

Straps should be used sparingly, if at all ; as the
shrinkage of the wood leaves them loose, and
the work is liable to settle. In most examples of
old carpentry, these were freely used ; but modern
methods of framing with rods and bolts have ob-
viated the necessity for them, so that they are now
but rarely employed.

114

ROOFS.

PLATE VI.

Fig. 3 of this plate exhibits a design for a roof of
from forty to sixty feet span. Being very simple in its
construction, it is more frequently used than any other.
The trusses should be not more than eight or ten feet
apart, and the common rafters twenty inches apart, from
centres.

Table of dimen

in inches, of limbers for roofs of various
spans.

NAMES.

Span in Feet.

40

45

50

55

60

Tie-beams ....
Truss-rafters . . .
Collar-beams . . .
Common Eafters . .

6x8
6x7
6x7
2x6
5x7
3x6
4x6
lin.
iin.

7x8
7x7
7x7
2x6
6x7
4x7
5x7
Uin.
|in.

8x9
8x8
8x8
2x6
6x8
4x8
5x8
Uin.
fin.

8x10
8x9
8x9
2x7
6x8
5x8
5x8
Uin.
lin.

9x11
9x9
9x9
2x7
6x9
5x9
6x9
Uin.
Uin.

Struts

Strengthening-pieces
Rods
Bolts . '

Fig. 1 exhibits in detail the framing at A, and Fig. 2
that at B.

Pl.TE

' ~|

pp«

LOOFS

ROOFS.

115

PLATE VH.

Fig. 2 exhibits a design for a roof of from thirty-
five to fifty feet span. This roof, from its simplicity and
strength, is, like that on Plate VL, much approved,
and in common use.

Table of timber-dimensions for various spans.

Span i

i Feet.

35

40

45

50

Tie-beams ....

6X7

6x8

7X9

8x9

Truss-rafters . .

6X6

6x7

7X8

8x8

Common Rafters ....
Struts . .

2X6
2x6

2X6
3X6

2X6
3X6

2X6
4X6

Purlins

4X7

5X7

6X7

6X8

Rod

r jn

1 in

li in.

Hin.

Bolt

1 !

4 in

3 in

i in

1 in

Fig. 1 exhibits an example of a roof, with tie-beams,
so framed as to admit of finishing a curved ceiling. The
practice of thus dispensing with a horizontal or single
tie-beam should be used with great caution, as the work
is always liable to settle.

Table of limber-dimensions for various spans.

NAMES.

Span in Feet.

40

45

50

Tie-beams

6X8
6X7
2X6
2X6
5X7
4X6
1 in.
fin.

6X9

6X8
2X6
3X6
6X7
5X6
l|in.
iin.

6X10
6X9
2X6
4X6
6X8
6X6
Uin.
1 in.

Truss-rafters

Common Rafters

Struts

'. Purlins

Rods

Bolts

116

HOOFS.

PLATE VHI.

Fig. 3 exhibits a design for a roof, with inclined tie-
beams,* and, having been executed many times with
perfect success, may be considered as entirely reliable
for any span of less than seventy-five feet. The tie-beams
are halved together; and the planks at the intersection
should be of dry white oak or chestnut, bolted to the
beams with bolts five-eighths of an inch in diameter. The
centre rod should be made forked at the lower end, one
part passing down outside of each plank, with an eye on
each tine, through which passes a bolt, crossing the beams,
and supporting them at the intersection. It is apparent,
that, so long as the distance from C to D remains the
same, no settling can take place, or thrust be exerted on
the side-walls.

Table of timber-dimensions for various spans.

Span in Feet.

NAMES

40

45

50

55

60

65

70

Tie-beam

6X8

6X9

7X10

7X11

8X10

8X11

9X12

Truss- rafter

6X7

6X8

7X9

7X10

8X9

8X10

9X10

Com. Rafter

2X6

2X6

2X6

2X7

2X7

2X8

2X8

Collar-beam

6X7

6X8

7X9

7X10

8X9

8X10

9X10

Purlins .

5X7

5X8

6X8

6X8

6X8

6X9

7X9

Struts . .

3X6

3X6

3X7

4X7

4X8

6X8

5X9

Long Rods

lin.

l*in.

1| in.

1| in.

l£in.

If in.

l|in.

Short „

Jin.

lin.

lin.

lin.

If in.

l] in. 14 in.

Bolts . .

fin.

fin.

Jin.

fin.

lin.

1£ in.

IJln.

* This roof was executed first at the Unitarian church of
Sornerville, Mass., in the year 1850, from drawings furnished
by the author; the leading idea having been suggested by Rev.
Augustus R. Pope, minister of the society. A very heavily
stuccoed ceiling is appended to it, but, after a test of six
years, is as perfect as when first built.

PI. IX

HOOFS

ROOFS. 117

PLATE IX.

Fig. 1, on Plate IX., is a design for a low roof of wide
span. The figures show the dimensions of timber for one
of from sixty-five to seventy-five feet. It may be ex-
tended to ninety feet by a proportional increase in the
size of the rods and timbers.

Fig. 2 shows a roof of from eighty to a hundred and
twenty feet span. The figures on the engraving are cal-
culated for one of a hundred feet, and should be increased
or diminished according to its width.

The tie-beam in this design should be made of two
four-by-fourteen-inch planks, with short pieces of two-inch
planks at intervals between them.

Some of the bearings in each of these examples are
designed to be of cast iron, as will be discovered by con-
sulting the drawing.

118 ROOFS.

PLATE X.

Plate X. exhibits two designs for curved roofs. The
tie-beams of each are in two pieces, with a two-inch plank
between them; and the struts, where they cross, are
notched into each other, so that their sides may be flush
with those of the beams.

Fig. 1 represents a segmental roof. The figures denote
the size of timber for a span of seventy-five feet. If the
span be increased to ninety feet, the size of the timber
should be increased about one-seventh. The trusses may
be placed ten feet apart; and the rafters, two by eight
inches, notched two inches below the top of the curved
rib. The purlins at aaa should be six by six inches:
they are designed to give firmness to the roof at the
joints. The bearings at bb, &c., are of cast iron.

Fig. 2 shows a design for a roof of from seventy to a
hundred and twenty-five feet span. It is so designed,
that a room may be finished above the tie-beams.
If the span be great, with a room as proposed, the cen-
tre of the beam between the rods must be trussed, as
shown in the examples on Plate V. ; and the floor-joists
should bridge upon, rather than cut into, the tie-beams.

It will be seen, by an examination of the plate, that at
the line AB there is a tie-beam, which, with the work
above it, comprises a segmental roof, complete in itself;
and its rise may be increased as circumstances require.
The dimensions designated by the figures are for a roof
of eighty feet span, and should be increased one-eighth
for a span of a hundred feet, and one-fifth for one of a
hundred and twenty-five feet, — the rods being increased
in the same proportion.

ROOFS

Pl.X

PI. XI.

ROOFS

KOOFS. 119

PLATE XI.

The figures on this plate exhibit the design of a
portion of the large trusses which support the dome of
the State Capitol at Montpelier, Vt.* The span is sixty-
seven feet four inches between the walls, and the trusses
receive no support from below. The bearing-pieces are
of white oak, the rest of the timber being spruce. Each
truss is composed of two parts, or sections, like those re-
presented by the designs. The beams are placed fourteen
inches apart, with short transverse ones extending from
one to the other, as at aa, &c., with another crossing
them, as sedh at A. Upon the beams last named stand
the posts of the dome, which, when finished, will be forty-
two feet in diameter. Its frame being octagonal, the two
front and two rear posts are nearer together than the
others, and consequently require a differently constructed
truss. The student will readily discover, on examination,
the manner in which the particular strains are resisted
by the several parts of the work.

* These trusses, together with the framing of the roof and
dome, employing eighty thousand feet of timber, were exe-
cuted by Mr. Eobert Gunnison, the master-carpenter, under
the direction of Thomas E. Powers, Esq., the superintendent
of construction, from drawings furnished by the author in
1857.

120 ROOFS.

PLATE XH.

Fig. 1 of this plate shows the design of a roof over
the Fitchburg Depot in this city. It was executed from
drawings furnished by Mr. Charles G. Hall in the year
1848. The second floor of the building (some eighty feet
wide, and a hundred and fifty feet long) is supported
entirely by rods from the tie-beams. It has been loaded
with people, at an average of a hundred and twenty-five
pounds to the square foot, without any settlement what-
ever. The trusses are ten feet apart from centres.

Fig. 2 shows the roof of the Boston and Maine Rail-
road Depot, in Haymarket Square, Boston. It was
executed from drawings made by Mr. Richard Bond,
architect of the building. The trusses are twelve feet
apart from centres. This roof remains as firm in every
part as when first built; and, considering the quantity
of timber used, it is a good roof.

The figures on each of these designs exhibit the dimen-
sions of each part as taken from actual measurement.

ROOFS

pi.xa

ROOFS

Fig!.
E H F

~B

Wg.2.

Jt

—--- -k'-^ef D/ <^

Fig.5.

Snith . Blnilu

ROOFS. 121

PLATE XIH.

Figs. 1, 2, and 3 of this plate exhibit a method of
drawing the angle-ribs of a roof, the outline of which is
AH; and a portion of the plan, DEFG. Divide BH
into any number of parts, as 1, 2, 3, 4, and draw lines
through these points to the angle-line FB. From the
points of intersection, on and at right angles with the
line last named, draw abed equal to 1, 2, 3, 4, measuring
from BH to AH. Trace a line through the points, and
the angle-rib is formed.

Fig. 5 illustrates the method of ascertaining the length
and back of the angle-rafters of a hip-roof.

Let AB represent the pitch of the roof. From C, the
corner of the plan, draw CD ; and from D draw DE per-
pendicular to CD, equal to AB : from this point draw
EC, which is the rafter required. To determine the back
of the rafter, we proceed as follows : Draw ab perpen-
dicular to CD. On the centre c, with a radius Sc6 (the
edge of the rafter) describe the semicircle fed; then from
e draw ea and eb, which will be the angle of the rafter
at e.

Where the plan of a roof is bounded by lines which are
not parallel, it is the usual practice, jn order that the
sides of the roof may be of the same inclination, to trun-
cate the work, as shown at A, Fig. 4.

122 ROOFS.

PLATE XIV.

Fig. 1 of this plate exhibits a design for a roof of
large span. The figures designate the dimensions of tim-
ber for a span of eighty feet. With a proportionate
increase of the size of rods and timber, it may with safety
be extended over a span of a hundred and twenty-five
feet. The beam should be made in two sections, the
centre portion between the rods trussed, and an oak-
plank three inches thick bolted to the top of the beam,
as seen at AB.

Fig.l

n

Kgr-2.

IP

E

Rg.3.

J

123

PARTITIONS.

IN cases where a large partition cannot have a
proper support from below, — as, for example,
where it stands over a hall or large room, — it
should be trussed, so that its entire weight shall
rest on the points of support.

Figs. 2 and 3, Plate XIV., exhibit two designs for par-
titions, which will readily be understood without further
explanation.

124

DOMES.

To frame a dome is one of the simplest branches
of the art of carpentry. It was, however, till a late
day, thought to require great ingenuity and scientific
skill.

A dome is, in all directions from the centre of
its plan, an arch : hence it is possessed of great
strength ; and, if properly constructed, its lightness
is its greatest recommendation. The dome of the
State House at Boston is a fine specimen of framing.
Its span is fifty-one feet, its height from the floor
nearly the same; and, with the exception of the
four posts which support the lantern, no timber is
used larger than three inches thick, and twelve
inches wide. Every other rib is at the base of
these dimensions, the alternate ones being two by
twelve inches. All are placed three feet apart
on the circle, and taper to about eight inches wide
at the top, where they are cut against a curb,

DOMES. 125

being there, about twelve incnes apart from
centres.

The scarfs are similar to Fig. 2, Plate XX., and
are bolted together with bolts half an inch in dia-
meter, with plank two inches thick, spiked on each
side of the ribs over the scarfing.

The rough boarding is horizontal ; and, after
enduring the storms of more than half a century,
the structure has proved itself well adapted to its
intended purpose. Were the dome larger, the
size of its timbers would not necessarily have been
increased, since the principles of the arch pervade
the whole. A more complicated framing would have
detracted from its merit as a design, since all that
can be desired is accomplished by the present one ;
and so simple are the principles involved, that it has
not been thought necessary to illustrate them by an
engraving.

Where a dome rests upon a high drum, like that
of the Capitol at Montpelier, it may be necessary,
if the structure stands in an exposed situation, to
provide a skeleton-frame of posts, girts, braces, &c.,
in order to strengthen the work.

BRIDGES AND CENTERINGS.

129

BRIDGES.

THE designing of wooden bridges was for many
years intrusted to the architect, but has, of late,
been considered as more properly belonging to the
engineer. As the mechanical part of bridge-build-
ing must be done by the carpenter, a few examples
are given in illustration of his province. Most of
them have been designed for this work ; and those
remarks which have been made in reference to
other descriptions of framing will apply equally
well to this.

9

130 BRIDGES.

PLATE XV.

Fig. 1 of this plate represents what is familiarly known
as " Howe's Bridge" taking its name from its inventor.
The stringers A and B are of planks three inches thick,
bolted together. These planks are of different lengths ;
and the joints should be well broken. The struts cross
each other, without being notched or cut into ; and, at
their ends, they abut against a piece of white oak, as at C,
Fig. 2. The rods are two in number to each section, as at
DD, Fig. 3. The height of the sides, or trusses, should
be about one-twelfth of the entire length of the span.
The stringers should be wide enough to come out flush
with the sides of the struts, and the oak-pieces must be as
long as the stringers are wide. The depth of the stringer
should be two-thirds of its width; and the struts one-
twelfth the height of the truss, measuring between the
stringers as ef. The diameters of the rods should be
one-fourth that of the struts. An oak-piece, two inches
thick and three inches and a half wide, is put at the nut
at each end of the rod, as at g, Fig. 3.

Fig. 2 is the detail of the work at F ; and Fig. 3, a
sectional detail of that on the line HI. The figures on
the engraving denote the dimensions of timber for a
bridge a hundred feet long, eight feet high, and ten feet
wide in the clear. Should a wider bridge be required,
the number of sections must be increased. It is often
the practice to place the floor-joists on the top of the
upper stringer, instead of below ; in which case, rails, or a
balustrade, will be required.

Fig. 4 exhibits a design for a short bridge of from
twenty-five to forty-five feet span. It is made by placing

BRIDGES. 131

one timber above another, as shown in the drawing.
The timbers being inclined, with oak-keys between them,
and bolted together, a very strong truss is formed. The
trusses should be about four feet apart, and the floor-
joists three inches thick and twelve inches wide, placed
twenty inches apart. These dimensions are for a bridge
of thirty feet span.

Fig. 5 exhibits a design for a common gallery truss.
The bearing-pieces should be of oak.

The dimensions are for a truss of sixty feet span. It
may be made somewhat flatter, if desired, and still be
sufficiently strong for practical purposes.

132 BRIDGES.

PLATE XVI.

The figures on this plate exhibit designs for bridges of
from fifty to ninety feet span. Should it be desired, the
floor-timbers of Fig. 2 may be placed upon the centre
rail, and the work above them will answer for the rails
of the bridge : if this be done, the centre rails will need
additional support by bracing. The dimensions are for
bridges of sixty feet span ; all the bearing-pieces being
of the best dry and sound white oak, bolted with five-
eighth-inch iron bolts. It may be well to remark here,
that the floors of all bridges require strong horizontal
braces from the side-stringers, crossing each other at the
centre in order to prevent vibration.

BRIDGE S

PI. AM

i 1

u

•H

^ L-

A

N

F1.ZVE

BRIDGES

Kg.l.

Kg.3.

BRIDGES. 133

PLATE XVII.

Fig. 1 represents a side-view of a timber-bridge over
the river Meuse, in France. Its span is sixty feet, and its
width twenty-eight feet. Each arch has four trusses.

Fig. 2 exhibits the design of a bridge over the river
Rhone, in France. It is similar in principle to the ex-
ample at Fig. 1, the trusses being secured by transverse
timbers bolted together.

Fig. 3 represents a bridge over the river Loiret, near
Orleans in France. Its span is sixty feet, and its width
six feet six inches.

Fig. 4 shows part of a lattice-bridge invented by Mr.
Ithiel Towne, of New Haven, Conn. Its span may be
from seventy-five to a hundred and fifty feet. The lattice-
framing is of planks three inches thick, and twelve inches
wide, so arranged as to cross each other at right angles.
They are confined together at the intersecting parts by
oak tree-nails, an inch and a half in diameter, passing
through each of the planks. The depth of the lattice-
work should be about an eighth of the entire span.
Plank-ribs are used at top and bottom on each side of
the lattice-work ; the sides being connected, top and
bottom, at distances of twelve feet, by cross-timbers,
and braced horizontally with diagonal braces. A bridge
of this kind exists at Philadelphia, eleven hundred feet
long, resting on ten stone piers. There is also another
on the New -York and Harlem Railroad, seven hundred
and thirty-six feet long, resting on but four piers.

134

BRIDGE-CENTERINGS.

A CENTERING is a frame of timber designed to sup-
port the stones of an arch while building. Where
the bed of the river is not very deep, nor the tide
strong, a centering may be made at small expense ;
but in other circumstances, and where the span is
large, a more complex and expensive system of
framing must be adopted.

In the construction of a centering, the principal
object is so to arrange the timbers that a weight or
pressure, when exerted upon any particular part,
may be resisted, and the structure retain its original
form throughout ; and it should be so designed as to
admit of removal without injury to the work rest-
ing upon it. In most examples, this is done by the
insertion of a piece at the springing points, cut on
its sides into a series of inclined planes : over these,
oak wedges are driven, which, being easy of re-
moval, admit the uniform releasing of every part
of the work.

PI XVlli

CEMRES

BRIDGE-CENTERINGS. 135

PLATE XVIII.

Fig. 1 of this plate exhibits a centre designed by Mr.
Smeaton, architect of the celebrated Eddystone Light-
house. It is familiarly known as the " Cold-Stream
Centre," taking its name from the river over which the
bridge was built. The span of the large or middle arch
is sixty feet eight inches. The bridge is twenty-five feet
wide outside ; and, in its construction, five centres were
used to each arch.

Fig. 2 exhibits a centre used in building the arches of
a railroad-bridge over the river Ouse, near York, England.
The bridge consists of three arches, each sixty-six feet
span ; the soffit of the arch (or width of bridge) being
twenty-eight feet seven inches.

Fig. 3 is a design for a centre given by Mr. Tredgold,
which may be used for any span short of seventy-five feet

136 BRIDGE-CENTERINGS.

PLATE XIX.

Fig. 1 exhibits a part of one of the centres used in
the construction of London Bridge. It was designed by
Mr. Rennie in 1826. The width of the bridge, from " out
to out," is fifty-six feet. The middle or centre one of its
five arches is a hundred and fifty-two feet span, and has
a rise of twenty-nine feet six inches. Each arch used
eight centres, composed of fir ; the springing-pieces being
of elm, and the striking-wedges of oak.

Fig. 2 exhibits the design of a centre executed by Mr.
Thomas Telford in building a stone bridge at Gloucester,
England. The bridge consists of a single arch of a
hundred and fifty feet span, with a rise of thirty-five
feet. It is thirty-five feet wide; and six centres were
used, connected by cross-bars and caps, and the whole
steadied by diagonal braces. Between the timber which
rested on the top of the piles, and the lower horizontal
timber of each centre, were placed the wedges, which,
being driven back, slackened it after the stone-work was
completed. The piles were of Memel fir, shod with iron
at each end, and the remainder of the work of Dantzic
fir ; the whole being fifteen inches square. Each centre
was framed entire ; and then, by the aid of barges and two
cranes on the shore, was lifted into its place.

Fig. 3 exhibits a centering, simple in construction, but
of great utility. It may be employed to advantage wher-
ever the bed of the river can be used, and the tide is not
too strong; and for any span from a hundred to two
hundred feet.

Fi.HX

Snridi.Kiaght 8c Tampan . Emgt1

JOINTS, IRON-WORK, AND
TIMBER-TABLES.

139

JOINTS IN FRAMING.

NOTHING is more essential to the permanency of
a piece of carpentry than properly made .joints.
If the parts do not so fit together that each may
have its full bearing, the structure will inevitably
be weak. The examples on this plate are designed
to represent in detail the best manner of forming
joints of the various kinds most in use.

140 JOINTS IN FRAMING.

PLATE XX.

Fig. 1 represents the framing at the foot of the rafters
of Fig. 1, Plate XIV. abed is a cast-iron shoe, or box-
ing. AAA are oak-keys, two inches square. BB are
wrought-iron straps, in place of which bolts may be
used if desired.

Fig. 2 exhibits the method of splicing an upright
timber; as, for instance, a tower-post. The length of
such a splice should be three times the diameter of the
stick, and bolted together with half or five-eighth inch
bolts.

Fig. 3 illustrates a method of framing work at the
foot of the rafters of a common roof. This method is
much used. Each timber is to be notched into a half-
inch to receive the purlin.

Fig. 4 shows the manner of framing a centre-bearing
like that at A, Fig. 2, Plate VII. ; or B, Fig. 5, Plate XV.

Fig. 5 exhibits the method of framing the foot of the
rafters in a roof having inclined beams, as the example
on Plate VIII.

Fig. 6 shows the detail of a piece of framing, as at
AB, Fig. 1, Plate VII. At A is an oak-key two inches
square.

Fig. 7 is the detail of framing at the intersection C of
the plate before referred to ; E being a wrought-iron
strap, three-eighths of an inch thick and three inches
wide, made in two parts, with shoulders, and a small bolt
at a for securing the work.

:

fig.3.

141

IRON.

As cast and wrought iron are used in all heavy
framing, a few pages of this work will be devoted
to a consideration of its nature and properties.

Iron is a metal found in nearly all parts of the
world. Its specific gravity is .7632 ; being, with
the exception of tin, the lightest of all metals : and
it differs from them all in the fact, that, while they
are made brittle by the action of heat, its mallea-
bility is thereby greatly increased.

Iron shrinks so much in cooling, that a pattern
for castings should be made an eighth of an inch
larger per foot than the piece is required to be
when cooled. It is heated so as to appear red in
the dark at 752° Fahrenheit ; and, in twilight, at
884°. It is made visibly red-hot by day at 1,077°,
and is thoroughly melted at 2,754°.

Cast iron expands T^sWtf °f *ts length, in each
direction, for every degree of heat ; and its greatest

142 IRON.

expansion is T^TF °f ^ts length in the shade, and
TuVo- °f its length when exposed to the sun. It
will bear an extension of T^^ of its length with-
out permanent or serious alteration.

Wrought iron expands T4sW^ °f its length for
each degree of heat. It will bear an extension of
TiVo^ °f its length, and a pressure of 17,800 pounds
to a square-inch, without injury. Its cohesive
power is diminished ^^TF ^7 every degree of
heat.

The resisting power of cast iron has been greatly
overestimated. The best experiments show that a
force of 93,000 pounds to a square-inch will crush
it, and that it will not bear more than 15,300
pounds without visible alteration.

The tensile strength of wrought-iron rods has
been tested in a variety of ways. It has been
decided that no particular amount can be named as
the actual strain a rod will resist, as it has been
repeatedly proved that no rod is to be depended
upon as uniformly perfect throughout, a lesser
strain often parting a rod of larger diameter. The
cohesive power of cast iron is set down by most
authors at 40,000, and of wrought iron at 60,000,
ppunds to a square-inch. A vertical rod, having a
weight suspended at the lower end as in the case

IRON.

143

of rods supporting a tie-beam, not only supports
the weight at the end, but must, in addition, sustain
its .own weight from the point at which it is sus-
pended ; so that a long rod will part near the upper
sooner than the lower end. A perfect rod, there-
fore, decreases in strength as it is longer, and vice
versa. The iron-work in the examples of framing
given in this work is so figured as properly to sup-
port the work, and, at the same time, prevent un-
necessary vibration.

The following table shows the weight of a
square-foot of cast or wrought iron plate, from
a sixteenth of an inch to an inch in thickness,
advancing by sixteenths : —

Dimens. Wrought.

Cast.

Dimens.

Wrought.

Cast.

16ths.

Ibs.

Ibs.

leths.

Ibs.

Ibs.

1

2.5

2.3

9

22.8

21.1

2

5.1

4.7

10

25.4

23.5

3

7.6

7.0

11

27.9

25.8

4

10.1

9.4

12

30.4

28.1

5

12.7

11.7

13

32.9

30.5

6

15.2

14.0

14

35.5

32.9

7

17.9

16.4

15

38.0

35.2

8

20.3

18.0

16

40.6 •

37.6

144

IRON.

The following table shows the weight of a foot
in length of wrought or cast iron, either round or
square, from half an inch to three inches in dia-
meter, advancing by eighths : —

WROUGHT.

CAST.

Side of Square
or Diameter.

Circular.

Square.

Side of Square
or Diameter.

Circular.

Square.

Inches.

Ibs.

Ibs.

Inches.

Ibs.

Ibs.

£

.65

.83

k

.61

.78

&

1.02

1.3

ft

.95

1.22

|

1.47

1.87

4

1.38

1.75

|

2.

2.55

I

1.87

2.39

1

2.61

3.33

1

2.45

3.12

1J

3.31

4.21

H

3.1

3.95

14

4.09

6.2

4

3.83

4.88

If

4.94

6.3

i§

4.64

5.9

1*

5.89

7.5

i|

5.52

7.03

If

6.91

8.6

it

648

8.25

11

8.01

10.2

14

7.51

9.57

If

9.2

11 71

11

8.62

10.98

2

10.47

13.33

2

9.81

12.5

2|

11.82

15.05

2£

11.08

14.11

24

13.25

16.87

12.42

15.81

2|

14.76

18.8

2f

13.84

17.62

24

1636

20.8

24

15.33

19.53

1

18.03
19.79
21.63

22.96
25.2
27.55

2|
24
2§

16.91
18.56
20.28

21.53
23.63
25.83

3

23.56

30.

3

22.08

28.12

A cubic-foot of cast iron weighs 450.5 pounds ;
and one of wrought, 486.8. A cubic-inch of each
weighs respectively .260 and .281.

IRON.

145

The accompanying table shows the weight of
bar-iron from a quarter of an inch to an inch in
thickness, and from one to four inches in width,
advancing by an eighth: —

Width of
Bar.

Thick.

4 in.

Thick.

fin.

Thick.

Jin.

Thick.

fin.

Thick.

, fin-

Thick,
fin.

Thick.

lin.

in.

.84

1.25

1.66

2.08

2.5

2.91

3.31

|

.93

1.4

1.87

2.34

2.81

3.28

3.75

^

.04

1.56

2.08

2.6

3.12

3.64

4.16

a

.14

1.71

2.29

2.86

3.4

4.01

4.58

|

.25

1.87

2.5

3.12

3.75

4.37

5.

|

.35

2.03

2.71

3.38

4.11

4.73

5.42

I

.45

2.18

2.91

3.64

4.37

5.1

. 5.83

1|

.66

2.34

3.12

3.90

4.73

5.46

6.25

2

.77

2.5

3.33

4.16

5.

5.83

6.66

2|

.87

2.21

3.54

4.42

5.36

6.19

7.08

2-i

.98

2.81

3.75

4.68

5.62

6.56

7.5

2|

2.08

2.97

3.96

4.94

5.98

6.92

7.91

24

2.18

3.12

4.1G

5.2

6.25

7.29

8.33

2|

2.29

3.28

4.37

5.46

6.61

7.65

8.75

21

2.4

3.43

4.58

5.72

6.87

8.02

9.16

2&

2.5

3.59

4.79

5.98

7.26

8.38

9.58

3

2.6

3.75

5.

6.25

7.5

8.75

10.

3J

2.7

3.91

5.21

6.51

7.86

9.11

10.42

34

2.81

4.06

5.41

6.77

8.12

9.47

10.83

3|

2.91

4.22

5.62

7.03

8.39

9.83

11.24

3|

3.01

4.37

5.83

7.29

8.75

10.2

11.66

3|

3.11

4.56

6.04

7.55

9.10

10.56

12.08

3|

3.22

4.68

6.25

7.81

9.37

10.93

12.5

3J

3.30

4.84

6.46

8.07

9.64

11.30

12.92

4

3.34

5.

6.66

8.32

10.

11.66

13.33

The weights in the foregoing tables are those of
English iron. American iron is a seventieth heavier;
and therefore, in making calculations of its weight, one
pound should be added to every seventy pounds as com-
puted by the tables.

To ascertain the weight of any piece of cast iron, we
have but to determine the contents in cubic inches, and
10

146 IRON.

multiply it by the decimal .260 ; or in feet, and multiply
by 450.5. If it be of a shape or form that will readily
admit of measurement in superficial feet as plates, we
select the multiplier for the particular thickness as given
in the table, and the product is the weight in pounds.

To determine the weight of a piece of wrought iron,
we ascertain its contents in cubic inches, and multiply it
by the decimal .281 ; 'or in feet, and multiply by 486.8;
or, if it admits of measurement as a plate, multiply the
amount of superficial feet by the figures set against the par-
ticular thickness in the table. To determine the weight
of any piece of round, square, or flat iron, we select the
amount given in the table, and multiply it by the number
of feet in length of the piece whose weight we wish
to obtain.

147

TABLES OF TIMBER-MEASURE.

THE accompanying tables exhibit the scantling, or dimensions,
of building-timber reduced to board-measure. The figures
in the left-hand column of each section represent the length of
the piece in feet; those of the right-hand column, the contained
quantity in feet and inches ; and those over the head of each
section, the thickness and depth of the piece in inches. The
decimals denote twelfths of a foot. Thus, a stick, seven by
nine inches square and nine feet long, contains forty-seven
feet and three-twelfths of a foot.

If it is desired to know the quantity contained in sticks of
greater length than those given in the tables, this may be
ascertained by adding the amount of two or more requisite
lengths together.

2X2

2X3

2X4

!

2X5

2X6

1 .

1

0.4

li 0.6

li 0.8

1

0.10

1

1.

2

0.8

2 1. -1

1.4 i

2

1.8

2

2.

3

1.

3i 1.6

! 3

2.

3

2.6

3

3.

4

1.4

4 2.

j 4

2.8 |

4

3.4

4

4.

5

1.8

5

2.6

i 5

3.4

5

4.2

5

5.

6

2.

6

3.

! 6

4.

6

5.

6

6.

7

2.4

7

3.6

7

4.8

7

5.10

7

7.

8

2.8

*

4.

8

5.4

8

6.8

8 8.

9

3.

9

4.6

9

6.

9

7.6

9 9.

10

3.4

10

5.

10

6.8

10

8.4

10

10.

11

3.8

11

5.6

11

7.4

11

9.2

11

11.

12

4.

12

6.

12

8.

12

10.

12

12.

13

4.4

i:;

6.6

!13

8.8

13

10.10

13

13.

14

4.8

14

7.

14

9.4

14 11.8

14

14.

15

5.

15

7.6

15 10.

15

12.6

15

15.

16

5.4

16 8.

16 10.8

16

13.4

16

16.

17

5.8

17

8.6

17

11.4

17

14.2 i

17

17.

18

6.

18

9.

•18

12.

18

15.

18

18.

19 i 6.4

19

9.6

19

12.8

19

15.10

19 19-

20 i 6.8 i

20

10.

20 13.4

20 16.8 |

20 i 20-

148

TABLES OF TIMBER-MEASURE.

2X7

2X8

2X9

2X10

2X11

1

1.2

1

1.4

1

1.6

1

1.8

1

1.10

2

2.4

2

2.8

2

3.

2

3.4

2

3.8

3

3.6

3

4.

3

4.6

3

5.

3

5.6

4

4.8

4 5.4

4

6.

4

6.8

4

7.4

5

5.10

5

6.8

5

7.6

5

8.4

5

9.2

6

7.

6

8.

6

9.

6

10.

6

11.

7

8.2

7 9.4

7

10.6

7

11.8

7

12.10

8

9.4

8 10.8

8

12.

8

13.4

8

14.8

9

10.6

1 9i 12.

9

13.6

9

15.

9

16.6

10

11.8

10 13.4

10

15.

10

16.8

10

18.4

11

12.10

11 14.8

11

16.6

11

18.4

11

20.2

12

14.

12 16.

12

18.

112

20.

12

22.

13

15.2

13 17.4

13

19.6 1 13

21.8 i 13

23.10

14

16.4

14 18.8

14

21.

14

23.4 14

25.8

15

17.6

< 15 20.

15

22.6

15

25. I 15

27.6

16

18.8

16 21.4

16

24.

16

26.8 ! 16

29.4

17

19.10

17 22.8

17

25.6

17

28.4

17

31.2

18

21.

18 24.

18

27.

18

30.

18

33.

19

22.2

j 19 25.4

19

28.6

19

31.8

19

34.10

20

23.4

20

26.8

20

30.

20

33.4

20

36.8

2X12

2X13

2X14

3X3

3X4

1

2.

1

2.2

1

2.4

1

0.9

1

1.

2

4.

2

4.4

2

4.8

2

1.6

2

2.

3

6.

3

6.6

3

7.

3

2.3

3

3.

4

8.

4

8.8

4

9.4

4

3.

4

4.

5

10:

5

10.10

5

11.8

5

3.9

5

5.

6

12.

6

13.

6

14.

6

4.6

6

6.

7

14.

7

15.2

7

16.4

7

5.3

r

7.

8

16.

8

17.4

8

- 18.8

8

6.

8

8.

9

18.

9

19.6

9

21.

9

6.9

9

9.

10

20.

10

21.8

10

23.4

10

7.6 :

10

10.

11

22.

11

23.10

11

25.8

11

8.3 j

11

11.

12

24.

12

26.

12

28.

12

9.

12

12.

13

26.

13

28.2

13

30.4

13

9.9

13 13.

14

28.

14

30.4

14

32.8

14

10.6

14 14.

15

30.

15

32.6

15

35.

15

11.3

15

15.

16

32.

16

34.8

16

37.4

16

12.

16

16.

17

34.

17

36.10

17

39.8

17

12.9

17

17.

18 36.

18

39.

18

42.

18

13.6

18

18.

19

38.

19

41.2

19

44.4

19

14.3

19

19.

20

40.

20

43.4

20

46.8

20

15.

20

20.

TABLES OF TIMBER-MEASURE.

149

3X5

3X6

3X7

3X8

3X9

1

1.3

1 1.6

1 1.9

1

2.

1

2.3

2

2.6

2 3.

2! 3.6

2

4.

1 2

4.6

3

3.9

3! 4.6

3 5.3

3

6.

' 3

6.9

4

5.

4| 6.

4 7.

4

8.

4

9.

5

6.3

5 7.6

5 8.9

5

10.

5

11.3

6

7.6

6 9.

6 10.6

6

12.

6

13.6

7

8.9

7

10.6

7 12.3

7

14.

7

15.9

8

10.

-

12.

8 14.

8

16.

! 8

18.

9

11.3

9

13.6

9 15.9

9

18.

; 9

20.3

10

12.6

10

15.

;10 17.6 10

20.

10

22.6

11

13.9

11

16.6

11 ! 19.3

11

22.

11

24.9

12

15.

12

18.

' 12 ! 21.

12

24.

12

27.

13

16.3

13

19.6

• 13 22.9 13

26.

13

29.3

14

17.6

14

21.

14 24.6

14

28.

14

31.6

15

18.9

15

22.6

15 26.3

15

30.

15

33.9

16

20.

16

24.

i!6i 28. l»;

32.

16

36.

17

21.3

17

25.6

17

29.9

17

34.

17

38.3

18

22.6

18

27.

!18

31.6

18

36.

18

40.6

19

23.9

19

28.6

19

33.3

19

38.

19

42.9

20 | 25.

20

30.

20

35.

20

40.

20

45.

1

3X10

3X11

3X12

3X13 3X14

j

1

2.6

1

2/9

1

3.

1! 3.3

i 1

3.6

2

5.

2

5.6

2

6.

2 6.6

; 2

7.

3 7.6

3

8.3

I 3

9.

3 9.9

3

10.6

4

10.

4

11.

4

12.

4 13.

4

14.

5

12.6

5

13.9

5

15.

5 16.3

5

17.6

6

15.

6

16.6

6

18.

6 19.6

i 6

21.

7

17.6

7

19.3

7

21.

7; 22.9

j 7

24.6

8

20.

8

22.

8

24.

1 8 26.

i 8

28.

9

22.6

9

24.9

9

27.

, 9 29.3

9

31.6

10

25.

10

27.6

ilO

30.

10 32.6

10

35.

11

27.6

11

30.3

111

33.

11 35.9

11

38.6

12

30.

12

33.

12

36.

12 39.

'12

42.

13

32.6

.13

35.9

13

39.

13 42.3

13

45.6

14

35.

14

38.6

14

42.

14

45.6

14

49.

15

37.6

15

41.3

15

45.

15

48.9

115

52.6

16

40.

16

44.

16

48.

16

52.

16

56.

17

42.6

17

46.9

!17

51.

17

55.3

17

59.6

18

45.

18

49.6

!l8

54.

118

58.6

18

63.

19

47.6

19

52.3

19

57.

|19 61.9

19

66.6

20

60.

20

55.

j 20 60.

20 65.

20

70.

150

TABLES OF TIMBER-MEASURE.

4X4

4X5

4X6

4X7

4X8

1

1.4

1

1.8

1

2.

1

2.4

1

2.8

2

2.8

2

3.4

-2

4.

2

4.8

2

5.4

3

4.

3

5.

3

6.

3

7.

3

8.

4

5.4

4

6.8

4

8.

4

9.4

4

10.8

5

6.8

5

8.4

5

10.

5

11.8

5

13.4

6

8.

6

10.

6

12.

6

14.

6

16.

7

9.4

K

11.8

7

14.

7

16.4

7

18.8

8

10.8

8

13.4

8

16.

8

18.8

8

21.4

9

12.

9

15.

9

18.

9

21.

9

24.

10

13.4

10

16.8

10

20.

10

23.4

10

26.8

11

14.8

11

18.4

11

22.

11

25.8

11

29.4

12

16.

12

20.

12

24.

12

28.

12

32.

13

17.4

13

21.8

13

26.

13

30.4

13

34.8

14

18.8

[14

23.4

14

28.

14

32.8

14

37.4

15

20.

15

25.

15

30.

15

35.

15

40.

16

21.4

lie

26.8

16

32.

16

37.4

16

42.8

17

22.8

17

28.4

17

34.

17

39.8

17

45.4

18

24.

18

30.

18

36.

18

42.

18

48.

19

25.4

19

31.8

19

38.

19

44.4

19

50.8

20

26.8

20

33.4

20

40.

20

46.8

20

63.4

4X9

4X10

4X11

4X12

4X13

1

3.

1

3.4

1

3.8

1

4.

1

4.4

2

6.

2

6.8

2

7.4

2

8.

2

8.8

3

9.

3

10.

3

11.

3

12.

3

13.

4

12.

4

134

4

14.8

4

16.

4

17.4

6

15.

5

16-8

5

18.4

5

20.

5

21.8

6

18.

6

20.

6

22.

6

24.

6

26.

7

21.

7

23-4

7

25.8

7

28.

7

30.4

8

24.

8

26-8

8

29.4

8

32.

8

34.8

9

27.

9

30.

9

33.

9

36.

9

39.

10

30.

10

33.4

10

36.8

10

40.

10

43.4

11

33.

11

36-8

11

40.4

11

44.

11

47.8

12

36.

12

40.

12

44.

12

48.

12

52.

13

39.

13

43.4

13 47.8 |

13

52.

13

56.4

14

42.

14

46.8

14

51.4

14

56.

14

60.8

15

45.

15

50.

15

55.

15

60.

15

65.

16

48.

16

53.4

16 58.8

16

64.

16

69.4

17

51.

17

56.8

17 62.4

17

68.

17

73.8

18

54.

18

60.

18 66. .

18

72.

18

78.

19

57. 1 19

63.4

19 69.8

19

76.

19

82.4

20

60. 20

66.8 |

20 73.4 i

20

80.

20

86.8

[I

I

TABLES OF TIMBER-MEASURE.

151

4X14

5X5

5X6 5X7

5X8

1

4.8

1 2.1

1

2.6

1

2.11 ! 1 i 3.4

2

9.4

! 2 4.2

2

5.

2

5.10 i 2 i 6.8

3

14.

! 3 6.3

3

7.6

3

8.9 3 10.

4

18.8

4

8.4

4| 10.

4

11.8

4 13.4

5

23.4

5 10.5

5

12.6

5

14.7

5

16.8

6

28.

6 12.6

6

15.

6

17.6

6

20.

7

32.8

71 14.7

7

17.6 ! 7

20.5

7

23.4

8

37.4

8

16.8

8

20.

8

23.4

i 8

26.8

9 42.

9

18.9

9

22.6

9

26.3

! 9

30.

10 ' 46.8

10

20.10 10

25.

10

29.2

10

33.4

11

51.4

11 22.11

11

27.6 11

32.1

11

36.8

12

56.

12 25.

12 30. 12

35.

12

40.

13

60.8

13

27.1

13 32.6

13

37.11

!l3

43.4

14

65.4

14

29.2

14

35.

14

40.10

14

46.8

15

70.

15 31.3

15

37.6

'is

43.9

;15

50.

16

74.8

16

33.4

16

40.

16

46.8

16

53.4

17

79.4

17

35.5

17

42.6

!17

49.7

17

56.8

18

84.

18

37.6

18

45.

18

52.6

i!8

60.

19

88.8

19

39.7

19 47.6

•19

55.5

19

63.4

20

93.4

20

41.8

20

50.

?20

58.4

;20

66.8

SX9

5X10

5X11

i

5X12

5X13

1

3.9

1

4.2

1

4.7

1 5.

1 1

5.5

2

7.6

2

8.4

2

9.2

2 10.

^ 2

10.10

3

11.3

3

12.6

3

13.9

3 15.

3

16.3

15.

4

16.8

4

18.4

4 20.

4

21.8

5 18.9

5

20.10

5

22.11

5 25.

; 5

27.1

6 22.6

6

25. l! 6

27.6

6L 30.

i 6

32.6

7 26.3

7 29.2

7 32.1

7 35.

7

37.11

8 30.

8 33.4

8 36.8

8 40.

8 43.4

9 33.9

9 37.6 9 41.3

9 45.

1 9 48.9

10 37.6

10

41.8 ! 10 45.10 10 50.

1 10 54.2

11 > 41.3 11

45.10 11

50.5 ' 11 55.

; 11 59.7

12| 45.

12

50. 12

55. i 12 60.

1 12 65.

13 i 48.9

13 54.2

13 59.7 113, 65.

1 13 70.5

14 52.6 14 58.4

14! 64.2 14 70. 14 75.10

15

56.3 15 62.6 15 68.9 15 75. 15 81.3

16

60. 16 66.8 16 73.4 i 16 80. 16 86.8

17

63.9

17 ; 70.10 17

77.11 ;17

85.

17 92.1

18

67.6

18 75. !18

82.6 |!18

90.

18 97.6

19

71.3

19 | 79.2 ; 19

87.1 ''19

95.

19 102.11

20

75.

20 I 83.4 20

1 II

91.8 j 20

100.

20

108.4

152

TABLES OF TIMBER-MEASURE.

5X14

6X6

6X7

6X8

6X9

1 5.10

1

3.

1

3.6

1

4.

1

4.6

2 i 11.8

2| 6.

2

7.

2

8.

2

9.

3

17.6

3

9.

3

10.6

3

12.

3

13.6

4

23.4

! 4

12.

4

14.

4

16.

4

18.

5

29.2

5

15.

6

17.6

5

20.

5

22.6

6

35.

6

18.

6

21.

6

24.

6

27.

7

40.10

7

21.

7

24.6

7

28.

7

31.6

8

46.8

8

24.

8

28.

8

32.

8

36.

9

52.6

9

27.

9

31.6

9

36.

9

40.6

10

58.4

10

30.

10

35.

10

40.

10

45.

11

64.2

11

33.

11

38.6

11

44.

11

49.6

12

70.

12

3*6.

12

42.

12

48.

12

54.

13

75.10

13

39.

13

45.6

113

52.

13

68.6

14

81.8

14

42.

14

49. 14

56.

14

63.

15

87.6

15

45.

15

52.6

15

60.

15

67.6

16

93.4

16

48.

16

56.

16

64.

16

72.

17

99.2

17

51.

17

59.6

17

68.

17

76.6

18

105.

'18

54.

18

63.

18

72.

18

81.

19

110.10

19

57.

19 66.6

19

76.

19

85.6

20

116.8

20

60.

20| 70. 20

80.

20

90.

1

6X10

6X11

6X12

6X13

6X14

1

5.

1

5.6

1

6.

1

6.6

1

7.

2

10.

2

11.

2

12.

2

13.

2

14.

3

15.

3

16.6

3

18.

3

1 19.6

3

21.

4

20.

4

22.

4

24.

4

26.

4

28.

5

25.

5

27.6

5

30.

5

32.6

5

35.

6

30.

6

33.

6

36.

6

39.

6

42.

7

35.

7

38.6

7

42.

7

45.6

7

49.

8

40.

8

44.

8

48.

8

52.

8

56.

9

45.

9

49.6

9

54.

9

58.6

9

63.

10

50.

10

55.

10

60.

10

65.

10

70.

11

55.

11

60.6

11

66.

11

71.6

11

77.

12

60.

12

66.

12

72.

12

78.

12

84.

13

65.

13

71.6

13

78.

13

84.6

13

91.

14

70.

14

77.

14

84.

14

91.

14

98.

15

75.

15

82.6

15

90.

15

97.6

15

105.

16

80.

16

88.

16

96.

16

104.

16

112.

17

85.

17

93.6

17

102.

17

110.6

17

119.

18

90.

18

99.

18

108.

18

117.

18

126.

19

95.

19

104.6

19

114. 19

123.6

19

133.

20

100.

20

110.

20

120.

20

130.

20

140.

i ' '

1 ;

I

i

TABLES OF TIMBER-MEASURE.

153

' i ' '!

7x7

7X8

7X9

7X10 7X11

1

4.1

! i

4.8 1

5.3 1 ; 5.10 1 6.5

2

8.2

2

9.4

2

10.6

2 11.8

i 2 12.10

3

12.3

3

14.

3

15.9

! 3

17.6

3 19.3

4

16.4

4

18.8 4

21. 4 23.4 4 25.8

5 I 20.5

5

23.4 5

26.3 5 29.2 i 5 32.1

6

24.6

6

28.

! 6

31.6 6 : 35. 6 38.6

7

28.7

7 i 32.8

7

36.9

7

40.10 7 44.11

8

32.8

8

37.4 ' 8

42.

8

46.8 8 51.4

9

36.9

9

42. i 9

47.3

9

52.6

; 9

57.9

10

40.10

!10

46.8 10

52.6

10

58.4 10

64.2

11

44.11

111

51.4 • 11

57.9

11

64.2 11

70.7

12

49.

1 12

56. ' 12

63.

12

70.

12

77.

13

53.1

113

60.8 13

68.3 13

75.10 13

83.5

14

57.2

14

65.4 I 14

73.6

14

81.8 14

89.10

15

61.3

15

70. i 15

78.9 l.j

87.6 15

96.3

16

65.4

16

74.8 ! 16

84. i 16

93.4

16

102.8

17

69.5

17

79.4 ! 17

89.3 17

99.2

; 1 f

109.1

18

73.6

18

84. i 18

94.6

18 105. 18

115.6

19

77.7

'19

88.8 i 19

99.9

19 110.10 i 19

121.11

20

81.8

20

93.4 20

105. 20

116.8

j 20

128.4

7 X12

7X13

7x14

8X8

8X9

1

7.

1

7.7

r 8.2

1

5.4

1

6.

2

14.

2

15.2

2 16.4

2

10.8

2

12.

3

21.

3

22.9

• 3 24.6

3

16.

3

18.

4

28.

4

30.4

4 32.8

4

21.4

4

24.

5

35.

5

37.11

1 5 40.10

5 26.8

5

30.

6

42.

6

45.6

6 49.

6 32.

i 6

-36.

7

49.

7

53.1

1 7 57.2

7

37.4

1 1

42.

8

56.

8

60.8

8i 65.4

8

42.8

8

48.

9

63.

9

68.3 9 73.6

9 48.

! 9

54.

10

70.

'10

75.10 10 81.8

10 53.4

10

60.

11

77.

111

83.5 i 11 89.10 11

58.8

11

66.

12

84.

; 12

91. 12 98. jj 12

64.

12

72.

13

91.

;13

98.7 13 106.2 ! 13 69.4 i 13

78.

14

98.

14

106.2 14 114.4

14' 74.8 1,14 84.

15

105.

!lo

113.9 i 15 122.6

15 i 80.

15 90.

16

112.

16

121.4 i 16 130.8

164 85.4

16 96.

17

119.

17

128.11: 17 138.101117 90.8

17 i 102.

18

126.

18

136.6 |j 181 147. 18

96.

18 108.

19

133.

119

144.1 1 19 I 155.2 19 j 101.4

i 19 1 114.

20

140.

20

151.8 : 20 163.4 20 i 106.8

i 20 ! 120.

i

i

154

TABLES OF TIMBER-MEASURE.

8X10

8X11

8X12 8X13

8X14

1

6.8

1

7.4

1

8.

1

8.8

1

9.4

2

13.4

2

14.8

2

16.

2

17.4

2

18.8

3

20.

3

22.

3

24.

3

26.

3

28.

4

26.8

4

29.4

4

32.

4

34.8

4

37.4

5

33.4

5

36.8

6

40.

5

43.4

5

46.8

6

40.

6

44.

6

48.

6

52.

6

56.

7

46.8

7

51.4

7

56.

7

60.8

7

65.4

8

53.4

8

58.8

8

64.

8

69.4

8

74.8

9

60.

9

66.

9

72.

9

78.

9

84.

10

66.8

10

73.4

10

80.

10

86.8

10

93.4

11

73.4

11

80.8

11

88.

11

95.4

111

102.8

12

80.

12

88.

12

96.

12

104.

12

112.

13

86.8

13

95.4

13

104.

13

112.8

13

121.4

14

93.4

1 14

102.8

14

112.

14

121.4

14

130.8

15

100.

15

110.

15

120.

15

130.

15

140.

16

106.8

16

117.4

16

128.

16

138.8

16

149.4

17

113.4

'17

124.8

17

136.

17

147.4

17

158.8.

18

120.

18

132.

18

144. i

18

156.

18

168.

19

126.8

!l9

139.4

19

152.

19

164.8

19

177.4

20

133.4

20

146.8

20

160.

20

173.4

1

20

186.8

9X9

9X10

9X11

9X12

9X13

1

6.9

1

7.6

1

8.3

1

9.

1

9.9

2

13.6

2

15.

2

16.6

2

18.

2

19.6

3

20.3

3

22.6

3

24.9

3

27.

3

29.3

4

27.

4

30.

4

33.

4

36.

4

39.

5

33.9

1 5

37.6

5

41.3

5

45.

5

48.9

6

40.6

6

45.

6

49.6

6

54.

6

58.6

7

47.3

7

52.6

7

57.9

7

63.

7

68.3

8

54.

8

60.

8

66.

8

72.

8

78.

9

60.9

9

67.6

9

74.3

9

81.

9

87.9

10

67.6

10

75.

10

82.6

10

90.

10

97.6

11

74.3

11

82.6

11

90.9

11

99.

11

107.3

12

81.

12

90.

12

99.

12

108.

12 1 117.

13 87.9

:13

97.6

13

107.3

13

117.

13 126.9

14 | 94.6

114

105.

14 115.6

14

126.

14 i 136.6

15 101.3

115

112.6

15

123.9

15

135.

15 I 146.3

16 1 108.

|16.

120.

16

132.

16

144.

16 ! 156.

17 114.9

17

127.6

17

140.3

17

153.

17 165.9

181121.6 '18

135.

18

148.6

18

162.

18 175.6

19 ! 128.3 19

142.6

19

156.9

19

171.

19 185.3

20 135. 20

150.

20

165.

20

180.

20

195.

TABLES OF TIMBER-MEASURE.

155

9X14

10X10

10X11

10X12

10X13

1

10.6 1

8.4

1

9.2

1

10.

1

10.10

2

21.

i 2

16.8

2

18.4

2

20.

2

21.8

3

31.6 3

25.

3

27.6

3

30.

3

32.6

4

42.

1 4

33.4

4

36.8

4

40.

4

43.4

5

62.6 5

41.8

5

45.10

6

50.

5

54.2

6

63. ! 6

50.

6

55.

60.

6

65.

7

73.6 7

58.4

7

64.2

7

70.

7

75.10

8

84. 8

66.8

8

73.4

8 80.

8

86.8

9

94.6 9

75.

9

82.6

9 90.

9

97.6

10

105. ! 10

83.4

10

91.8

10 ! 100.

10

108.4

11

115.6 11

91.8

11

100.10

11 110.

11

119.2

12

126.

12

100.

12

110.

12 120.

12

130.

13

136.6

13

108.4

13

119.2

13 130.

13

140.10

14

147. 14

116.8

14

128.4

14 140.

14

151.8

15

157.6 15

125.

15

137.6

15 150.

15

162.6

16

168.

16

133.4

16 146.8

16 160.

16

173.4

17

178.6

17

141.8

17

155.10

17 170.

17

184.2

18

189.

18

150.

18

165. 18 180.

IS

195.

19

199.6

19

158.4

19 174.2 19 190.

19

205.10

20

210.

20

166.8

20 183.4 |

20

200.

•1 >

216.8

10X14

11X11

11X12

11X13

11X14

1

11.8 1

10.1

1 11.

1

11.11

1

12.10

2

23.4

; 2

20.2

2 22.

2

23.10

•2

25.8

3

35.

3

30.3

3: 33.

3

35.9

3

38.6

4

46.8

! 4

40.4

4 44.

4

47.8

4

51.4

5

58.4

5

50.5

5i 55.

5

59.7

5

64.2

6

70.

6

60.6

6 66.

6

71.6

6

77.

7 81.8

7

70.7

7

77.

7

83.5

7

89.10

8

93.4

8

80.8

8

88.

8

95.4

8 102.8

9

105.

9

90.9

9 99.

9 107.3

9 j 115.6

10

116.8

10

100.10

10 110.

10 ! 119.2

10 128.4

11

128.4 11

110.11

11 121.

11 i 131.1

11 141.2

12

140.

12

121.

12 132.

12 143.

12 154.

13

151.8 13

131.1

13 143. 13 154.11

13 , 166.10

14

163.4 JIM

141.2

14 154. 1141166.10

14 179.8

15

175. ! 15

151.3

15 165.

15 I 178.9

15 192.6

16

186.8 16

161.4

16 176.

16 1 190.8

16 205.4

17 | 198.4

17

171.5

17 187.

17 I 202.7

17 218.2

18

210.

;18

181.6

18 198.

18 214.6

18 231.

19

221.8 19

191.7

19 209.

19 226.5

19 243.10

20

233.4 j 20

201.8

20 220.

20 ; 238.4

20 256.8

i

156

TABLES OF TIMBER-MEASURE.

12X12

12X13

12X14

12X15

13X13

1

12.

1

13.

1

14.

1

15.

1

14.1

2

24.

2 26.

2

28.

2

30.

2

28.2

3

36.

3 39.

3

42.

3

45.

3

42.3

4

48.

4| 52.

4

56.

4

60.

4

56.4

5

60.

5 65.

5

70.

5

75.

5

70.5

6

72.

6 78.

6

84.

6

90.

6

84.6

7

84.

7 91.

7

98.

7

105.

7

98.7

8

96.

8 104.

8

112.

8

120.

8

112.8

9 108.

9 117.

ii

126.

9

135.

9

126.9

10 : 120.

10 130.

10

140.

10

150.

10

140.10

11 132.

11 143.

11

154.

11

165.

11

154.11

12 144.

12 156.

12

168.

12

180.

12 169.

13 \ 156.

13 169.

13

182.

13

195.

13 183.1

14 168.

14 182.

14

196.

14

210.

14

197.2

15 ! 180.

15 195.

15

210.

15

225.

15 211.3

16 192.

16 208.

16

224.

16

240.

16

225.4

17 | 204.

17 221.

17

238.

17

255.

17

239.5

18 i 216.

18 234.

18

252.

18

270.

18

253.6

19 228.

19 247.

19

266.

19

285.

19

267.7

20

240.

20 260.

20

280.

20

300.

20

281.8

13X14

13X15

14X14

14X15

14X16

1

15.2

1

16.3

1

16.4

1

17.6

1

18.8

2

30.4

2

32.6

2

32.8

2

35.

2

37.4

3

45.6

3

48.9

3

49.

3

52.6

3

56.

4

60.8

4

65.

4

65.4

4

70.

4

74.8

5

75.10

' 5

81.3

5

81.8

5

87.6

5

93.4

6

91.

i 6

97.6

6

98.

6

105.

6

112.

7

106.2

I 7 113.9

7

114.4

7

122.6

7

130.8

8

121.4

! 8 130.

8

130.8

8

140.

8

149.4

9

136.6

i 9 146.3

9

147.

9

157.6

9

168.

10

151.8

10 1 162.6

10

163.4

10

175.

10

186.8

11

166.10

ill

178.9

11

179.8

11

192.6

11

205.4

12

182.

12

195.

12

196.

12

210.

12

224.

13

197.2

!13

211.3

13

212.4

13

227.6

13

.242.8

14

212.4

14

227.6

14

228.8

14

245.

14 !' 261.4

15

227.6

15

243.9

15

245.

15

262.6

15 ; 280.

16

242.8

16

260.

16

261.4

16

280.

16 \ 298.8

17

257.10

17

276.3

17

277.8

17

297.6

17 317.4

18 I 273.

18

292.6

18

294.

18

315.

18 336.

19 I 288.2

19

308.9

19

310.4

19

332.6

19 354.8

20 303.4

20

325.

20

326.8

20

350.

20 373.4

GLOSSARY OF TERMS

IN COMMON USE AMONG CAKPENTERS.

159

GLOSSARY.

A.

ADHESION. A physical term,
denoting the force with which a
body remains attached to another
when brought in contact. Cohe-
sion is the force that unites the
particles of a homogeneous body.
The insertion of a nail into wood
is accomplished by separating the
particles, and thereby destroying
the cohesion; and its extraction,
by overcoming the adhesion and
friction. Adhesion, as related to
woods, may be considered as fol-
lows : 3^. nails, 18 of which weigh
1 pound, 1£ in. long, when driven
£ in. into spruce, across the fibres
of the wood, require a force of 73
pounds to extract them. A Qd.
nail, driven 1 in. into dry oak,
resists a strain of 507 pounds ; and
when into dry elm, 378 pounds. I
If the same nail be driven into ;
elm endwise, or parallel with the
grain, it may be drawn out by a
strain of 2of pounds. The adhe-
sion, therefore, when driven into
the wood named, across the grain,
or at right angles to the fibres, is
greater than when driven parallel
with them, as 4 to 3. In dry
spruce, it is nearlv as 2 to 1. A
common screw, a fifth of an inch in
diameter, has an adhesion about
three times as great as a common
Gd. nail. If the nail last named
be driven 2 in. into dry oak, it will !
resist a direct strain of nearly half
a ton.

ADZE. An edged tool used by
carpenters to chip surfaces lying
in a horizontal position, or in
situations where they cannot easi-
ly be cut with an axe.

ANGLE. A term in geometry
signifying a corner, or the point
where two converging lines meet.
Angles are of three kinds; viz.,
riV/it, obtuse, and acute. A right
angle is formed by a line joining
another perpendicularly, or at an
inclination of 90°, which is one
quarter of a circle. In an obtuse
angle, the inclination of the lines
is greater or more open than 90°.
In acute angles, their inclination
is less than a right angle. A solid
angle is the meeting of three or
more plain angles at a point.

ANGLE-BRACE. A piece framed
across the angle of a piece of fram-
ing. It is also termed an ang-le-
tie, or diagonal tie, and is nearly
synonymous with brace.

ANGLE-RAFTER. A piece in
a hip-roof at the line where the
two adjacent inclined sides unite.
It is continued from the eaves to
the ridge, and serves to support the
jack-rafters.

APERTURE. An opening
through a wall or partition.
u Apertures," says Sir Henry
Wotton, "are inlets for air and
light: they should be as few in
number, and as moderate in di-
mensions, as may possibly consist
with other due respects ; for. in a
word, all openings are weakenings.

160

GLOSSARY.

They should not approach too
near the angles of the walls ; for
it were, indeed, a most essential
solecism to weaken that part which
must strengthen all the rest."

APRON. The horizontal piece
in wooden stairs supporting the
carriages at their landings.

ARC. A term in geometry sig-
nifying any portion of a circle, or
curve.

ARRIS. The intersecting line
where two surfaces of a body
meet.

ARRIS-FILLET. A piece of
wood, triangular in section, used
to raise the slates or shingles
which are against any portion of
the work projecting from the roof;
as a party-wall, sky -light, chim-
ney, battlement. &c.

ARTIFICER. ' One skilled in
any mechanical art ; an inventor,
or contriver.

ARTISAN . A mechanic trained
to manual dexterity in any art or
trade.

ASHLERING. The short studs
of a building between the plate
and girt of the attic-floor. Build-
ings are framed in this manner
where the attic is designed for oc-
cupation ; the short studs cutting
off the acute angle which the
rafters would make, were they
permitted to come to the floor.

AUGER. A tool used by car-
penters for boring holes.

AUXILIARY RAFTERS. Pieces
of timber framed in the same ver-
tical plane with principal rafters,
placed under and parallel to them I
to give additional strength to the I
truss. (See Plate XI.)

AXE. An instrument for hew- '
ing timber or chopping wood. The
axe is of two kinds ; the broad axe
for hewing (the handle of which j
is usually so bent as to adapt it j
for hewing either right or left),
and the narrow axe for cutting,
&c.

AXIS OF A DOME. A right
line passing through its centre,
and perpendicular to its base.

B.

BACK. The side opposite the
face of any piece of work. When
a timber is in a horizontal or in-
clined position, the upper side is
called the back; and the under
side, the breast. The top side or
surface of rafters, and the curved
ribs of ceilings or of hand-rails,
are called backs.

BACKING A HIP-RAFTER,
OR RIB. The act of forming the
upper surface of either in such a
manner as to make it range with
the backs of the rafters, or ribs,
on each side.

BALKS, or BAULKS. Small
sticks of roughly hewn timber,
being the trunks of small trees
partially squared. The term usu-
ally denotes sticks less than 10
in. square at the but, and taper-
ing a good deal as they approach
the other end.

BAR-POSTS. Posts fixed in
the ground at the sides of a field-
gate. They are mortised to re-
ceive the movable, horizontal bars.

BASIL. The slope or angle of
an edge tool, as that on a chisel
or plane-iron. The angle is usu-
ally 12° for soft and 18P for hard
wood.

BATTER. A term applied to a
wall which is not plumb or per-
pendicular on its face, but which
slopes from an observer standing
in front.

BAULK-ROOFING. A term in
use when timbers were generally
hewn, instead of sawn as at pre-
sent. It formerly designated a
roof framed of baulk-timber,
which, being hewn from small
trees, could not be formed into
square timbers, having an arris
full and square.

BAY. The space intervening
between two given portions of the
wall or floors of a building.

BAY OF JOISTS. The joist-
ing of a particular portion of a
building, as between the posts
of a side-wall or the girders of a
floor.

BEAM. A large and long piece
of squared timber, used in hori-

GLOSSARY.

161

zontal positions for supporting a
superincumbent weight, or for
counteracting two opposite forces,
tending either to stretch or to
compress it in the direction of its
length. Employed as a lintel, or
for the support of the ends of
joists in a floor, it simply sustains
a weight ; if employed as a tie-
beam to the truss of a roof, it re-
sists the strain or thrust exerted
by the truss-rafters; or, if as a
collar-beam between the heads of
truss-rafters, it resists the strain
they exert, and is compressed.

BEAM-COMPASS. An instru-
ment for describing circles of a
larger diameter than may be prac-
ticable with ordinary compasses.
It consists of a rod, or beam, on
which are two sliding sockets, one
provided with a sharp steel needle
for fixing the centre of the cir-
cle to be described, and the other
with a pencil for describing the
circle itself. A very common
method among carpenters for
marking large circles, such as
plans of domes, &c., is to de-
termine the centre, and then affix
to it the end of a slip or lath of
•wood, at the other extremity of
which is the instrument for tra-
cing the circle required.

BEAM-FILLING. The brick-
work about the rafters at the
eaves of a brick building.

BEAKER. Any timber or wall
that supports another timber, and
retains it in its proper place.

BEARING. The distance or
length which the ends of a timber
or joist rest on another, or are
inserted in a wall. A beam in-
serted 12 in. in a pier or wall is
said to have a 12 in. bearing.

BEETLE. A large and heavy
wooden mallet or hammer for
driving stakes, piles, wedges, &c.
It has one, two, or three handles,
as may be required.

BELFRY. The part or section
of a steeple in which the bell is
suspended. The term was for-
merly used to denote more parti-
cularly the framing to which the
bell was hung.

BELL-ROOF. A roof the ver-

tical section of which is concave
at the bottom, and convex at the
top. It is often called an ogee
roof.

BELVIDERE. A turret or lan-
tern used for an observatory ; also
an arbor or artificial eminence in
a garden.

BEVEL. An instrument of the
nature of a try-square, one leg
being movable on a centre, so
that it may be set at any angle.
The term also denotes an angle
which is more or less than a right
angle.

BINDING-JOISTS. In old me-
thods of framing, binding-joists
were large joists or timbers framed
between the girders, in a trans-
verse direction, for the support
of the floor-joists above, and the
ceiling-joists below. Thus method
of framing is now but seldom
used in this country.

BOARD. In America, a board
is a piece of timber of any length
or width, and from £ in. to 2 in.
in thickness. Pieces of 2 or more
in. up to 6 in. in thickness are
called planks. In England, a
board is a piece of timber more
than 4 in. in width, and may be
2J in. thick ; and all boards wider
than 9 in. are called planks.

BOARDING-JOISTS. The same
as floor- joists.

BOLT. A square or round iron
pin, with a head or flange at one
end, and a thread and nut at the
other.

BOND. Any thing that con-
nects and retains two or more
bodies in a particular position.

BOND-TIMBERS. The tim-
bers or pieces of wood which are
built into the walls of a brick
or stone building to secure the
internal finishing.

BONING. The act of judging
and forming a plain surface or
straight line by the eye. The art
is usually termed sighting. Car-
penters and joiners use for this
purpose two straight edges, by
which they determine whether the
surface is true or twisted

BORING. The act of perforat-
ing any substance. In joinery,

11

162

GLOSSARY.

this is done with a hrad-awl, gim-
let, or bit ; and in carpentry, by an
auger.

BOW. Any part of a building
that projects from a straight wall.
It may be either circular or po-
lygonal in plan: the last-named
are termed canted bows.

BRACE. A piece of timber
fixed across the internal angle of
the larger timbers of a frame ; by
which arrangement the whole of
the work is stiffened, and the
building prevented from swerving
either way.

BREAK IN. An old expression
in use among carpenters, signify-
ing the act of cutting or breaking
a hole into a brick or stone wall
to admit the ends of joists, beams,
&c.

BREAST-SUMMER. A piece of
timber used for sustaining a su-
perincumbent weight, and per-
forming the office of a lintel over
any large opening ; as large win-
dows, or doors in a store, or an
open passage-way under the se-
cond story of a building.

BBIDGE. A term denoting that
one timber lies across and im-
mediately upon another, or is
notched into it. Thus, in framed
roofing, the common rafters bridge
over the purlins, and the purlins
over the principal rafters.

BRIDGING. Pieces placed be-
tween timbers to prevent their
nearer approach. In floors, the
joists are often stayed in this
manner by pieces of the same
kind of joist cut and nailed in
between them at right angles, or
by narrow pieces of board placed
in a similar position, and diago-
nally crossing each other.

BRIDGING-FLOORS. Those
in whose construction bridging-
joists are used.

BRIDGING-JOISTS. Those sus-
tained by a beam beneath them.

BUILDING. A fabric or edifice
of any kind, constructed for occu-
pancy ; as a house, barn, church,
&c.

BULKER. A term in use in
some parts of England to denote
a beam or rafter.

BUTMENT-CHEEKS. The two
sides of a mortise in any piece of
framing.

BUT- END. The end nearest
the root of a tree.

BUTTRESS. A pier or external
support, designed to resist any
pressure from within which may af-
fect the wall or thing so supported.

o.

CALIBER. The greatest dia-
meter of any round body ; as of a
log or ball, or the bore of a gun.

CAMBER. An arch or curve
on the top of an aperture or of a
beam. A beam is said to be cam-
bered when it is hewn or bent so
as to form a slight curve.

CAMBER-BEAMS. Beams
which are cambered.

CAMBERATED. Archedor
vaulted.

CAMPANILE. Atovrerfor
bells. In Italy they are usually
separate from the church, and are,
in general, highly ornamented and
costly edifices. The celebrated
one at Cremona is 395 ft. high.
That at Florence, built from a de-
sign by Giotto, is 267 ft. high,
and 45 ft. square. The most re-
markable campanile in the world
is doubtless that at Pisa : it was
built about the year 1174, and is
commonly known as the " Leaning
Tower." It is cylindric in plan;
is 50 ft. in diameter, and 150 ft.
to the platform, on which are the
bells. From this platform a
plumb-line falls, on the leaning
side, nearly 13 ft. from its base.
Its entire height is 180 feet.

CAMPSHOT. The sill or cap
of a wharf or wall.

CANT. An external corner or
angle of a building. Among car-
penters, the term is also used to
denote the act of turning a piece
of timber.

CANTHERS. In ancient car-
pentry, the ends of the jack-
rafters of a roof. They are con-
sidered by some to have given
rise to the mutules of the
order.

GLOSSARY.

163

CAPSTAN. A strong and massy
column or cylinder of iron or
wood, at the top of which is a cir-
cular cap, with horizontal mortise?
or holes around it at equal dis-
tances to receive bars or levers, for
the purpose of turning it, and
thus winding up a rope, the other i
end of which is attached to the
weight to be raised, or to apply
the power of the machine to any
thing requiring removal.

CARCASS. The unfinished
state of a building before it is par- j
titioned off into rooms, the floors
laid, &c.

CARPENTER. In America this
word is often used indiscrimi-
nately to signify an artificer who
begins and completes the entire
wood-work of an edifice. The |
term properly denotes one who
does the framing, raising, board-
ing, and partitioning off the
rooms of a wooden building. The
finishing of its several parts is
done by the joiner. In ship-
building the carpenter hews out
the timbers, sets up the frame,
and planks it; while the ship-
joiner completes the work.

CARPENTER'S RULE. An in-
strument by the use of which
carpenters take dimensions, &c.
It is figured in inches, and parts
of inches ; and to some kinds is
affixed a slide, the figures upon
which enable the artificer to make
calculations in multiplication and
division, besides many others
which constantly occur in his
practice.

CARPENTER'S SQUARE. An
instrument made of steel, one leg
of which is 24 in. long and 2 in.
wide, and the other 16 in. long
and H in. wide; the legs being ;
figured in inches, and parts of i
inches. This instrument is used |
not only as a square and measur- ]
ing-rule, but, with a plummet and j
line, to determine levels. The
joiner's square has one leg of |
wood, and the other of steel with- ]
out figures.

CARPENTRY. The work per-
formed by carpenters, or the art
of hewing, framing, and joining '

the timbers, and ah1 the heavier
parts of a building. Also a struc-
ture of framed timbers ; as a
roof, a floor, or an arch-center-
ing.

CARRIAGE. The diagonally
notched plank which is placed in
an oblique position for the sup-
port of the treads and risers of a
flight of stairs.

CASSION. A large and strong
chest, made water-tight, and used
in the construction of the piers
of a bridge, where the rapidity
and depth of the river present a,
difficulty in building the founda-
tion. The floor of a cassion is so
constructed that the sides may be
detached from it when desired.
The bed of the river is levelled at
the site of the proposed pier; the
cassion is launched, and floated
to the location, and sunk. The
pier is then built therein as high
as the level of the water; the
sides of the cassion are then re-
moved, the pier resting on the
foundation prepared for it. The
tonnage of each of the cassions
used in the construction of West-
minster Bridge, over the Thames,
was equal to that of a forty -gun
ship.

CASTING. A term denoting
the bending or twisting of a board
or any piece of wood from its ori-
ginal state. It is synonymous
with warping:

CATENARY CURVE. The
curve formed by a chain or rope,
of uniform density, hanging freely
between two points of suspension.
Galileo is supposed to have been
its discoverer: and it is certain
that he proposed it as the proper
figure for an arch of equilibrium ;
supposing it, however, to be iden-
tical with the parabola. James
Bernonilli, an eminent mathe-
matician, born at Basil in 1654,
investigated its nature ; but its pe-
culiar properties were afterwards
demonstrated by John Bernouilli,
his brother. Their opinion was
adopted and advocated by Iluy-
gens and Leibnitz.

CEILING. The surface of a
room opposite the floor.

164

GLOSSARY.

CENTRE. A point which is
equally distant from the extre-
mities of a line, figure, or body :
the middle point or place of any
thing.

CENTERING. The temporary
frame or woodwork whereon any
arched work is constructed.

CHALK. A variety of carbon-
ate of lime. Red chalk is an
indurated or hardened ochre, and
takes its name from its color.
French chalk, used by tailors, is
a soft magnesian mineral, of the
nature of steatite, or soapstone.

CHAMFER. A furrow, slope,
or bevel. A beam or joist is said
to be chamfered when the arris
is so cut as to convert its original
right angle into an obtuse angle,
at the lines where the slope inter-
sects with the plane of the other
sides.

CHEEKS. Two upright, simi-
lar, and corresponding parts of
any timber-work ; such as the
studs at the sides of a door, win-
dow. &c.

CHIP. A piece of wood, or
other substance, separated from a
body by any cutting instrument.
As a verb, it signifies to separate
into small pieces or chips by gra-
dually hewing or cutting.

CHISEL. A well-known instru-
ment, made of iron, faced at the
bevel, or cutting end, with steel.
Those used for paring, being thin,
are called paring-chisels : those
used for framing are heavier and
thicker, being called firmer or
framing chisels.

CHIT. An instrument formerly
used for cleaving laths.

CHORD. The right line which
joins the two extremities of an
arc. It is so called from its re-
semblance to a bow and string,
the chord representing the string.

CIRCLE. A figure bounded by
one continued curved line, called
the circumference, all parts of
which are equidistant from a
point called the centre. It is the
most capacious of all plain figures.
The circumference of any circle,
divided by 3.1416, will give the
diameter; or the diameter, multi-

plied by the same number, will
give the circumference. In com-
mon practice, where great exact-
ness is not required, it is usual to
consider the diameter to the cir-
cumference as 22 to 7.

To find the area of any circle,
multiply half the diameter by
half the circumference ; or, for a
more accurate calculation, inul-
ti ply the square of the diameter
by .7854, or the square of the
circumference by .07958. Squar-
ing the circle, as it is termed, is
the attempt to ascertain the exact
contents of a circle in square
measure, — a problem as yet un-
solved.

CLAMP. A piece of wood so
fixed to another that the fibres
or grain of one may cross those
of the other, and thus prevent its-
warping or twisting.

CLEAR. The clear or unmo-
lested distance between any two
surfaces or points. The net dis-
tance between a floor and ceiling
is said to be the height of the
story in the clear.

CLERE-STORY. A con-
tinuation of the nave, choir, and
transepts of a church, above the
roof of the aisles.

CLEAVING. The act of sepa-
rating, by force, one part of a
piece of wood or other substance
from another, in the direction of
its fibres.

CLEFTS. Those cracks or fis-
sures produced in wood when
wrought too green ; or when, in
an unseasoned state, it is exposed
to sudden heat. In thin stuff, as
boards, &c., the clefts, being some-
what different from those in fram-
ing lumber, are usually termed
sh akes.

COCKING. A method of con-
fining the tie-beams of a roof to
the top of the wall-plates, or the
joists of a floor to the girders and
girts, by dove-tailing the parts
together. Its design is to prevent
the walls from spreading.

COLLAR-BEAM. A beam used
to prevent the bending or sagging
of the rafters in a common roof,
or the nearer approach of the tops

GLOSSARY.

165

of the rafters in one that is
trussed.

COMPASSES. A mathematical
instrument for describing circles
and measuring distances. Com-
mon compasses need no descrip-
tion. Triangular compasses have,
in addition to the two legs of com-
mon ones, another, made with a
joint, and movable in any direc-
tion. > Beam compasses are de-
signed for describing large circles.
(See description.) Proportional i
compasses have two pairs of legs, j
connected by a shifting centre
sliding in a groove, and thereby
regulating the proportion which
the opening or distance between
the joints at one end bears to that
at the other. They are used to
enlarge or diminish drawings to
any given scale.

COMPRESSIBILITY. The qua-
lity of being compressible, or the
capacity of being reduced to
smaller dimensions. A post sus-
taining a heavy superincumbent
weight, or the collar-beam or
strut of a truss-roof, when in use,
are said to be in a state of com-
pression.

CONCU3. This term is doubtless
derived from the Latin concutio,
to shake or shatter. In carpen-
try, it properly denotes wood so
rotten or decayed in some of its
parts as to be shaky. Of late
years, it is generally used to signify
rotten or decayed knots; and
boards or sticks of timber having
such knots are termed concussed.

COXE. A solid body having a
circle for its base, and terminating
at its top in a point, or vertex.

CONICAL ROOF. A roof whose
exterior surface is formed like a
cone.

CONSTRUCTION. The act of
building, or of devising and form-
ing. Among architects, the term
more generally denotes the ar-
ranging and distributing of the
parts of a building in such, a man-
ner as will insure durability to
the structure, and economy in the
use of its materials.

CONSTRUCTITE CARPENTRY.
Practical or operative carpentry.

CONTACT. A touching or
juncture of two bodies. Tnings
are said to be in contact when
parts of them are so near together
that there is no sensible interven-
ing space. The places where they
touch are called the points of con-
tact.

CONTOUR. The outline bound-
ing any figure.

CONTRACTION. The act of
drawing together or shortening,
by causing the parts of a body to
approach each other. Thus, in an
iron rod, heat, by insinuating it-
self between the particles of the
metal, causes the rod to become
longer ; and it is then said to be
expanded. Cold, which is simply
the absence of heat, causes or per-
mits the particles to come nearer
each other ; and the rod in this
state is said to be contracted.

CONVERGENT LINES. Lines
tending te one point, and which,
if continued, would meet.

COUNTER-SINK. To sink a
recess or cavity in any material,
for the reception of a projection on
the piece to be connected with it;
as the head of a screw or bolt, or
the plate of iron against which
the nut or head of a bolt is fixed.

CRADLING. The timber-ribs
to which are nailed the laths or
furrings of a vaulted ceiling.

CRAMP. An iron instrument
used by carpenters to draw or
force mortises and tenons toge-
ther. It is made of iron, with a
movable shoulder at one end, and
a screw at the other.

The term also denotes a piece
of iron bent at the ends towards
one side, and used to confine the
larger timbers of a frame toge-
ther.

CRANE. A machine for raising
great weights. It consists of a
stout upright shaft or post, termed
a puncheon, from which projects a
strong arm, or piece of timber,
furnished at the extremity with a
tackle and pulley.

CROSS-BEAM. A large beam
extending from wall to wall of a
building, or the girder holding
the sides of an edifice together.

166

GLOSSARY.

CROSS-GRAINED. A twisted
or irregular disposition of the
fibres of wood, as in that part of
a tree where the branches shoot
from the trunk*.

CROSS-SPRINGERS. Ina
groined ceiling, the ribs springing
from the diagonals of the piers or
pillars on which an arch rests.

CROWN OF AN ARCH. Its
highest point of elevation.

CUBIT. A lineal measure, of
different length in different na-
tions. In ancient architecture, it
was equal to the length of the
arm from the elbow to the extre-
mity of the middle finger, or about
18 in. According to Dr. Arbuth-
not, the Roman cubit was 17 4-10
in. ; and the Scripture cubit, a
little less than 22 in. The geo-
metrical cubit of Vitruvius was 6
ordinary cubits, or 9 ft.

CURB-ROOF. A roof having
two different slopes on each side.
It is identical with the gambrel-
roof.

CURB-PLATE. A circular
plate or curb, formed by scarfing
two or more curved pieces toge-
ther at their ends, or by uniting
together pieces of plank in layers,
breaking the joints as in brick-
work. Curb-plates are used at the
eye of domes, &c.

CURLING-STUFF. Wood in
•which the fibres, instead of being
straight, are winding, as where
the branches of trees shoot from
the trunk ; the spiral character
of the formation causing the wood
to wind or curl.

CURSOR. The sliding part of
beam-compasses, or that part of
proportional compasses by which
the points are set at a given ratio.

CURVE. A line that is neither
straight nor composed of straight
lines, but which bends continually
without angles.

CURVILINEAR. Bounded by
a curved line. Thus a roof is
curvilinear when its plan is either
circular or elliptical.

CUT-ROOF. One that is trun-
cated, having a flat on the top.

D.

DAM. A mole, bank, or wall
of earth, or a frame of wood, built
to obstruct a current of water,
and raise its level for driving ma-
chinery, &c.

DEAL. A term more commonly
used in England than in America.
It denotes the wood of the fir-
tree, when made into pla&ks or
boards. They are imported into
England from Christiana and
Dantzic, taking the names of Chris-
tiana deals and Dantzic deals. The
usual thickness of the former is 3
in., and their width 9 in. Those
of 1$ in. thickness are called
whole deals; and those of half
that thickness, slit deals.

DENSITY. A term in physics,
denoting the closeness or compact-
ness of the constituent parts of a
body. In philosophy, the density
of a body is the quantity of mat-
ter contained in a given bulk.
Thus, if a body of equal bulk or
size with another is of double
the density, it contains double the
quantity of matter. For example:
A cubic foot of oak is more dense,
and therefore contains more mat-
ter, than the same amount of pine ;
and a cubic foot of iron, being
more dense, contains more matter
than either. The weight required
to crush a piece of wood is rela-
tively as the density of the wood.
A block of pine, being less dense
than one of oak, is therefore more
easily crushed.

DERRICK. A machine used by
carpenters for raising any heavy
body ; as the larger timbers of a
frame, or sections of the frame
itself.

DESIGN. In architecture, a
term denoting a plan or represen-
tation of any building. The term
signifies either the general ar-
rangement of floors, or the ar-
rangement and disposition of the
windows, doors, &c., of a build-
ing.

DETAILS. Drawings made on a
larger scale than those which sim-
ply exhibit the design of a build-
ing. They are usually of the full

GLOSSARY.

167

size of the work to be executed, :
and are often termed working- i
drawings.

DIAGONAL. A right line so
drawn through a figure as to join
the two opposite angles. Euclid
used the term diameter in the |
same sense. In modern practice,
diameter applies more properly to i
circular, and diagonal to angular '•
figures.

DIAGONAL SCALE. A mea-
suring scale fornted by horizontal
lines, with diagonals drawn across
them. It is designed for particu-
larly accurate measurements.

DIAMETER. A right line pass-
ing through the centre of a figure,
and dividing it into equal parts.

DIMENSION. The extent or
size of a body ; or length, breadth, i
and thickness or depth. A point ;
has no dimensions ; a line has one
dimension, — namely, length ; a
superfiee (as the side of a squared
stick of timber) has two dimen-
sions, — length and breadth ; and a
solid (as the whole stick) has three
dimensions, — length, breadth, and
thickness. The word is generally
used in the plural, and denotes
the whole extent of, or space
occupied by, a body ; as the
dimensions of a room, house, or

DISCHARGE. To unload or
relieve ; as the removal of weight
from a beam, or other timber,
when too heavily loaded.

DISPOSITION. The manner
in which the several parts of a
body are placed or arranged.

DOME. The spherical or other
shaped convex roof over a circular
or polygonal building. A seg- \
mental dome is one whose rise or
elevation is less than one-half its !
diameter. A stilted or surmounted I
dome is higher than the radius of '<
its plan or base. The oldest dome
of which we are informed is that
of the Pantheon at Rome, which
was erected under Augustus, and
is still quite perfect. In the fol- ]
lowing table will be found the di-
mensions of several of the princi- i
pal domes of Europe. The heights
are given from the ground.

ft.d. ft.h.

Pantheon at Rome ... 142 143

Sta. Maria del Fiore at

Florence 139 310

St. Peter's at Rome ... 139 330

St. Sophia at Constanti-
nople 115 201

Baths of Caracalla (an-
cient) 112 116

St. Paul's, London ... 112 215

Mosque of Achmet ... 92 210

Chapel of Medici .... 91 199

Baptistery at Florence . 86 110

Church of Invalids at

Paris 80 173

DORMANT TREE. A word of
bad etymology, and nearly out of
use. It is synonymous with the
terms lintel and summer.

DOUBLE FLOOR. A floor con-
structed with binding and bridg-
ing joists.

DOVE-TAIL. A joint formed
like a dove's tail : hence its name.
It is made by so shaping the parts
of the wood to be joined, that,
when one is let into the other, it
cannot be drawn out by a direct
strain while its wedge-like form is
retained.

DO \VELS. Pins of wood or iron
which unite two boards or timbers
in such a manner as to disguise
the fastenings.

DRAFT. A drawing represent-
ing the plans, elevations, and sec-
tions of a building, drawn to a
scale, thus exhibiting all its parts
in the same relative proportion to
each other as they are intended
to be in the building itself. The
term " draught " signifies the same
thing.

DRAGON-BEAM. A piece ly-
ing in a horizontal position, and
framed diagonally from each of
the angles of a hip-roof to a piece
at right angles with it, and which
is framed across the corner from
one plate to the other. The tim-
ber into which the dragon-beam is
framed is called the anglr-tie.

DRAWB011E. To confine a te-
non to a mortise by means of a
pin through the parts, the hole in
the tenon being nearer the shoul-
der than the holes in the cheeks

168

GLOSSARY.

of the mortise are to the abut-
ment against which the shoulder
is to come.

DRIFT. The horizontal power
exerted by an arch when it tends
to overset, or spread apart, the pier
from which it springs. As a verb,
it denotes the act of driving out a
pin or wedge by a power exerted
against the smaller end.

DRUXEY. Timber in a state
of decay, having white, spongy
veins, is said to be druzey.

DRY-ROT. A disease in timber
which destroys the cohesion of its
parts, and reduces its substance
to a dry powder.

D \VANGS (Scotch). The short
pieces of board or joist used in
bridging the joists of a floor.

EAVES . The edge or lower bor-
der of a roof which so projects
from the face of a wall as to throw
off the water that falls on the
roof

EDGE. The space between the
lines of intersection of two sur-
faces or sides of a solid; being
that part or superfice of a rectan-
gular body which contains the
length and thickness ; and is either
straight or curved, according to
the contour of the. surfaces or
sides. The edge of a tool is the
part where the two surfaces meet
when ground to an acute angle.

EDIFICE. A word nearly sy-
nonymous with building, struc-
ture, or fabric. The term edifice
cannot, however, be applied with
propriety to ordinary buildings,
but rather denotes architectu-
ral structures of importance; as
large mansion-houses, theatres,
churches, &c

EFFECT. That quality in an
architectural composition which
is calculated to attract the atten-
tion of the beholder, and excite in
him the sensation intended by the
designer.

ELASTIC CURVE. The curve
or figure assumed by an elastic
body, as a lath, or thin strip of

•wood or whalebone, when one
end is fixed horizontally in a ver-
tical wall, and the other loaded
with a weight, by which the lath
is curved or bended.

ELASTICITY. The inherent
property or quality in a body by
which it recovers its former figure
or state after being relieved from
any pressure, tension, or distor-
tion. Elasticity is perfect only
where a body recovers its exact
original form ahd shape, and in
the time which was required to
produce the flexure or bending.
The quality of perfect elasticity ia
rarely, if ever, found. A steel rod
is said to be more elastic than one
of iron ; and a string of India-rub-
ber is more so than one of hemp
or cotton. Brittle is the opposite
of elastic ; and therefore a piece
of wood is more elastic than a
piece of glass.

ELEVATION. A drawing or
geometrical representation of a
side or end of any building. In
an elevation, every part of the
structure represented is supposed
to be directly opposite to, and on
a level with, the eye.

ELLIPSE. A figure produced
by a plane passing obliquely
through a cylinder ; being what is
commonly called an oval.

ENTER. The act of inserting
the end of a tenon into a mortise,
previous to its being driven in up
to the shoulder.

EXT R ADOS. The interior
curve, or back, of the stones or
voussoirs of an arch.

EYE OF A DOME. The open-
ing at its top inside the curb.

FABRIC. Any large or impor-
tant building.

FACADE (French). A term
denoting the principal or most
important front of a building; as
that which faces on a public
street, lawn, or garden.

FATHOM. A measure of length
comprising six feet. It is used
chiefly among seamen for mea-

GLOSSARY.

169

suring ropes and chains, and for
sounding the depth of water.

FELLING TIMBER. The act
of cutting down trees.

FiLLING-IN PIECES. The
short studs which are cut in
against the braces of a frame, or
the short pieces of rafters cut in
against the hips of a roof or
groin. The term is synonymous
with jack-timber.

FIRMER-CHISEL. A thick
and heavy chisel for framing.
(See CHISEL.)

FLANK. The part of a build-
ing that joins the front. The side
of a building is called the flank ;
and a geometrical elevation of the
same, a flank elecaUun.

FLEXIBILITY. The quality
in a body which admits its bend-
ing, or flexure.

FLEXURE. A winding, or
bending. The sag of a stick of
timber is called its flexure.

FLOOR. The lower horizontal
surface of a room. Carpenters
generally include in the term the
timbers and joists on which the
floor-boards are laid, as well as
the boards themselves. There are
as many respective floors to a
building as the building is stories
in height. The first is usually
called the entrance story ; and the
floor on which the principal draw-
ing-rooms are. the principal story.

FLOOR-JOISTS. Those joists
in modern carpentry supporting
the boards of the floor of which
thev are a part.

FLUSH. A term which signi-
fies that surfaces are on the same
plane or line. The studs of a
wooden building are said to be
flu.tfi with the posts and girts.

FOOT. A measure of length,
containing 12 English in., —
supposed to have taken its name
from the length of the human
foot. The term is also used to de-
note surface, or solidity; as a
square fnot, and a solid or cubic
font. The length of the lineal
foot varies in different countries.
The accompanying table contains
its dimensions, in English in., in
the principal cities of Europe : —

London 12 in.

Amsterdam ...... 11 2-10

Antwerp 11 3-10

Bologna 14 4-10

Bremen 11 6-10

Cologne 11 4-10

Copenhagen 11 6-10

Dantzic 11 3-10

Frankfort on the M. . 11 4-10

Madrid 12

Paris 12 1-12

FORE or JACK PLANE. The
plane used by carpenters to take
off the rough surface of boards
and timbers, preparatory to fi-
nishing them with the jointer and
smoothing-plane.

FOX-TAIL WEDGING. A me-
thod of securing a tenon in a
mortise. It is done by first split-
ting the end of the tenon, and
then introducing a wedge, a por-
tion of which is permitted to pro-
ject from the cleft. The tenon is
then put into the mortise, the back
or bottom of which, opposite the
end of the tenon, resisting the
head of the wedge, it is forced
into the split in the tenon, driving
its parts asunder ; and it is thus
compressed and held fast by the
cheeks of the mortise.

FRAME AND FRAMING. The
rough timber-work of any build-
ing, including roofs, partitions,
floors, &c. *

FURRING. Thin pieces of
wood nailed to beams or any tim-
bers falling back of the surface or
line they are intended to form,
either in consequence of sagging,
or from any original deficiency in
size. The term may be appropri-
ately applied to any pieces of wood
employed in bringing crooked or
uneven work to a regular surface.

FUST. A term used in some
parts of England to denote the
apex or ridge of a roof.

G.

GAUGE. An instrument for
drawing lines on any surface of a
piece of wood parallel to one of the
arrises of that surface.

170

GLOSSARY.

GABLE The vertical triangu-
lar piece of wall at the end of a
building, bounded by a horizon-
tal line level with the eaves, toge-
ther with the two inclined lines
of the roof.

GAIN. The term is probably
derived from the Welsh word
u £•««," a mortise, and "'^a/iM," to
contain: hence any piece of tim-
ber, having one or more mortises,
may be said to be gamed. Tn
England, the term more properly
applies to the bevelled shoulders
of a floor-joist, for the purpose of
giving additional resistance to the
tenon below it. In America, the
term is generally understood to
mean a notch or mortise cut into
the arris of a beam or timber to
admit the end of another. In
framing ordinary house and barn
floors, the joists are gained into
the sills and girders instead of
being mortised.

GAMBREL-1100F. (See CURB-
ROOF.)

GIMLET. A well-known instru-
ment used by carpenters and join-
ers for boring small holes.

GIRDER. The principal beams
or timbers in a floor into which
the joists are framed. Their chief
use is to lessen the bearing or
length of the joists.

GIRT. The term , when used to
denote the size of timber, signifies
the circumference, or distance
around the outside of the stick,
and applies to all timber, whether
round or square. Among Ameri-
can carpenters, the term is used to
designate those horizontal timbers
in the outside walls of a wooden
building which are framed in be-
tween the posts at the floors of
the several stories ; the timber
beneath the post being the sill,
and that immediately on its top
the plate. Into the top and bot-
tom edges of the girt the studs
are framed; and into its side, or
bridging it at the top, the ends of
the joists of the floor

GRAIN. The direction of the
lines or fibres of wood. Thus,
when those lines are straight and
parallel, the wood is said to be

straight- grained ; but, when they
are twisted or crossed, it is said to
be cross- grained,

GROIN. The curved line of in-
tersection where two arches cross
each other.

GROOVE. A sunken channel.

GROUND-PLAN. The horizon-
tal section of that part of a build-
ing lying next above the surface
of the ground. A story, of which
the floor is below the surface of
the ground, is called abasement.

H.

HALVING. A method of join-
ing timbers by cutting away a
portion of each, so that they may
lock into each other.

H A M M E R-B E A M. A short
timber often used in ancient tim-
ber-roofs at the foot of the princi-
pal rafters. They extend a short
distance out from the wall on the
inside of the building, and are
supported by a brace from the un-
derside.

HANDSPIKE. A lever of wood
for turning a windlass or capstan.

HEADWAY OF STAIRS. The
clear distance or vertical height
from the top of a given stair to the
ceiling above.

HEW. To cut with an axe or
hatchet so as to make an uneven
and rough surface straight and
true. The practice of hewing
timber for frames is nearly out
of use; most of that used at the
present day being sawed at a mill.
The modern carpenter is seldom
familiar with this process: still,
a competent knowledge thereof,
although not often needed, is
essential to a thorough under-
standing of his profession, and
should by no means be neglected.

HI P-RAFTER. A piece of tim-
ber placed between the two adja-
cent inclined sides of a hip-roof
to support the jack-rafters.

HIP-ROOF. A roof of which
the end of the sides is not termi-
nated by lines on the same plane
as the ends of the building, but
by hips formed by the other sides

GLOSSARY.

171

or ends inclining from 'the end-
plates to the ridge.

I.

INCH. A lineal measure. In
England and America, it is the
sum of the lengths of three barley-
corns, or the twelfth part of a foot.

INTER-JOIST. The space or
interval between two joists.

INTER-TIES. Short pieces of
joist or timber used in floors and
partitions to bind the work toge-
ther. The word is synonymous
with bridging.

IN THE CLEAR. A phrase
denoting the clear or unobstructed
distance between any two given
points. A room, the ceiling of
which is ten feet above the floor,
is said to be ten feet high ui the
cltar.

J.

JACK-PLANE. A plane used
to take off the rough surface of
wood previous to its being fin-
ished by the jointers and smooth-
ing-plane.

.) AC K-R AFTER. The shorter
rafters, which, in a hip-roof, are
cut in against the hip-rafters.

JACK-RIBS. The shorter ribs
of a groin, which are cut in against
the angle-rib of a groined ceiling.

JACK-STCDS. The shorter
studs in the side of a building,
which are cut in under or upon
the braces. &c.

JACK-TIMBER. Any piece of
timber in the frame of a building,
if cut short of its usual length,
receives the epithet jack

JAMB. The side of any open-
ing in a wall.

JAMB-POSTS. The posts at
the sides of a door to which the
jamb-linings are affixed.

JERKIN-HEAD. A roof the
end of which is constructed in
a shape intermediate between a
gable and a hip : the gable being
continued, as usual, up to the line
of the top of the collar-beam:

and, from this level, the roof is
hipped, or inclined backwards.
This form is rarely adopted, except
in some cottages, or in decorative
architecture.

JOGGLLJ. A joint so formed,
that, when its parts are joined, a
force applied perpendicular to that
which holds them together will
not cause them to slide past each
other. A strut of a truss-roof, or
a brace, when tenoned or let into
the wood against it at its end. in
any part of a building, may be
said to be joggled.

JOINER. A mechanic who fin-
ishes a building after it has been
framed, raised, and boarded by
the carpenter. The work per-
formed by the joiner is called
joinery.

JOINT. The place where two
surfaces meet.

JOINTER. The name of the
two larger planes used by joiners.
They are of two lengths; thus
taking, respectively, the names of
lung and short jointer.

JOISTS. Those smaller timbers
of a building, framed into the
girders and girts, to which the
floor-boards are nailed, or into
the plates and girts upon which is
nailed the outside boarding. The
term, in this country, generally
denotes any piece of timber more
than 2 and less than 6 in. square.
It is synonymous with the old
term juffers.

X.

KERF. The channel, or slit,
made in wood by the teeth of a
saw. The term is also used to
denote the notches usually made
in a stick of timber by the hewer,
before he takes off the larger
pieces between the kerfs.

KEY. A piece of wood ( usually
of oak) let into another to prevent
warping. It also denotes the
wedge-formed pieces sometimes
put into a mortise at the side of a
tenon to prevent its being drawn
back out of the mortise. Also
those square or round pieces usu-

172

GLOSSARY.

ally put through a scarfing to
prevent its parts sliding past each
other.

KING-POST. In old methods
of carpentry, the centre-posts in
a trussed roof. This post is also
known as curb-post and prick-
post.

LANDING. That part of a
floor at the termination of a flight
of stairs, either at the bottom or
top.

LANTERN. An erection on the
top of a roof or dome, having an
aperture for the admission of
light. Its plan may be either
circular, elliptical, square, or po-
lygonal.

LATH. Literally, a thin slip
of wood. In America, the word
is used almost exclusively to de-
note strips of Avood 4 ft. long, 1|
in. wide, and f of an in. thick,
used for covering the partition-
studs and furring, preparatory to
plastering. Laths of this kind
are cut from the refuse pieces of
timber called slabs, which are the
segmental pieces first cut from a
log previous to sawing it into
boards, &c. They are put up in
bundles of a hundred each. In
England, the term latli generally
denotes narrow strips of wood
nailed to the rafters to support
the slating or tiling of a roof; also
those which support plastering.

LEDGMENT. The development
of a body as stretched out or
drawn on a plane, so that the
arrangement of its parts, and the
dimensions of its different sides,
may be readily seen and ascer-
tained. The drawing of a roof,
as seen from a point over it. is
said to be a view of the same in
ledg-ment.

LEDGERS are, in scaffolding,
the horizontal pieces parallel to
the walls of the building. They
are nailed to the outside of the
poles, and opposite the end of
the brackets upon which the
floors of the scaffolding are laid.

LEVEL. A horizontal line, or
plane parallel with the horizon.
The term also denotes an instru-
ment used by artisans to decide
when lines or planes are of equal
elevation at both ends.

LINE. In geometry, a term
denoting a magnitude of but one
dimension, which Euclid defines
to be length without breadth or
thickness. The term also denotes
the twelfth part of a French in.
A right line is the shortest straight
line that can be drawn between
two given points A horizontal
line is one level or parallel with
the horizon. A line which is
plumb leans neither way, but is at
right angles with, or perpendicu-
lar to, a level line.

LINTEL. A horizontal piece
of timber or stone, over a door,
window, or other opening, to sup-
port a superincumbent weight.

LUMBER. The term in this
country is usually understood to
mean logs or timbers after they
are cut and sawed or split for
use, and applies to all descriptions
and dimensions; such as beams,
boards, joists, planks, shingles,
&c.

M.

M ROOF. A roof formed of
two common roofs by placing their
eaves against and parallel to each
other, like the letter W inverted
(M). The design of the M roof is
that a larger space or span may
be roofed over with light timber
than could safely be done were
the span covered with a single
pitched roof. By the use of the
M roof, a saving is also made in
the gable-end ; the sum of the
surface of the two gables of the M
roof being less than in one large
gable.

MALLET. A large wooden
hammer used by carpenters for
driving the chisel in mortising,
&c.

MANSARD ROOF. Identical
with the gambrel or curb roof.
The Mansard roof was so named

GLOSSARY.

173

from its inventor, Francis Man-
sard, who was born at Paris in
1645. His true name was Har-
douin Julius Mansart. He was
an eminent architect, and was em-
•ployed by Louis XIV. to build the
Palace of Versailles and the Hos-
pital of the Invalids. He died in
1708, at the age of sixty-three.

MENSURATION. The science
which teaches the methods of
calculating the magnitude of bo-
dies, lines, and superfices.

MODEL. A miniature pattern
of the whole or some part of a
building, showing how the work
is to be arranged and constructed.

MORTISE. A sinkage, or recess,
in a piece of timber to receive the
tenon, or end, of another stick.

N.

NAKED FLOORING. A term
denoting the timbers of a floor,
such as beams, girders, joists, &c.,
•before the boards are laid upon
them, or the furrings affixed be-
neath.

o.

OUT TO OUT. An expression
denoting the magnitude of any
body measured to the extreme
outside.

OUT OF WIND. An expression
used by artificers to signify that
the surface of a thing is a true
and perfect plane. A squared
piece of timber, which by any
means has become twisted, is said
to be winding.

P.

PALE. A sharp-pointed stake
of wood used for landmarks, &c.

PALISADE. A fence or fortifi-
cation made of stakes, sharpened,
and driven firmly into the ground.

PARALLEL. In geometry, a
tenn applied to lines or surfaces
which run in the same direction,
being at every point equidistant
from each other.

PARALLELOGRAM. Any four-
sided rectilinear figure whose op-
posite sides are parallel. The term
usually denotes a figure greater in
length than in width.

PARTITION. A wall dividing
one room from another. When a
partition is of great length, and
is unsupported from beneath, it
should be trussed : it is then called
a trussed partition.

PEDIMENT. The triangular
part of a portico, or roof, which
is terminated by the sloping lines
of the roof. Pediments may be
either triangular or segmental in
contour. The term gable is nearly
identical with pediment; but the
latter term more properly applies
to a gable when finished with
an entablature, taking-mouldings,
&c.

PENDENTIVE CRADLING.
The timber-work which supports
the laths and plaster of vaulted
ceilings.

PERPENDICULAR. A line, or
surface, falling on another at right
angles. The term also denotes a
line at right angles with the hori-
zon ; although, in the latter case,
the proper term is vertical.

PILES. Large unhewn timbers
driven into the earth, upon the
heads of which are laid the foun-
dation-stones of large buildings,
the piers of bridges, &c. Piles
are used where the soil is too loose
and spongy to insure the founda-
tion against settlement without
them. They are usually of oak
or spruce, and are from 7 to 15
in. in diameter. They are sharp-
ened at one end, and, if need be,
shod with iron, and hooped at the
top. They are then driven into
the ground, as far as possible, by a
machine, which lets a heavy weight
fall upon their heads from a
height of about 30 ft. Piles, when
driven so far below the surface of
the ground that water always re-
mains over them, are quite im-
pervious to decay. Nearly the
entire city of Amsterdam is built
on piles. The foundation-stones
of the new Custom House in Bos-
ton rest on more than three thou-

174

GLOSSARY.

sand. They are driven at dis-
tances of 2 ft. from centres.

PIN. A piece of wood, com-
monly of chestnut or oak, sharp-
ened at one end, and used to
confine timbers together. Pins
made by hand, and therefore left
somewhat rough, are preferable
to those made by a machine, as
the latter, being nearly smooth
and round, easily turn or work,
when the wood about them has
shrunk in drying; whereas those
made by hand are polygonal, and,
when driven into holes, their
angles cut into the wood, and
they are thereby effectually pre-
vented from turning. Small pins
are called pegs. The pins used
in ship-building are made by ma-
chinery, and are called treenails.

PITCH. In carpentry, the
term denotes the angle formed by
the inclined sides of a roof. In a
building where the extreme height
from the top of the rafters at the
ridge is one-third of the width of
the building at the eaves, from
u out to out," the roof is said to
be one-third pitch ; if one-quarter
the width, nnr-quartcr pilch. If
it be 10 ft. from the top of the
rafters to a line level with the
eaves, it is 10-ft. pitch.

PLAN. The representation of
the horizontal section of a build-
ing, showing the disposition of
the rooms by the arrangement
of the partitions, &c. The word
plan is quite extensive in its sig-
nification, and, as commonly used,
denotes the general idea; hence,
the design of the several parts of
a building, whether as regards
finish, arrangement of rooms, or
the composition as a whole, may
with propriety be termed its plan ;
but, among architects, the term
more properly denotes a drawing
exhibiting the form, arrangement,
and size of the rooms on the se-
veral floors. A representation of
a front or side is called an eleva-
tion.

PLANK. A piece of timber of
any length, having a width of
more than 6 in., and from 2 to 6
in. thick. If less in thickness

than 2 in., it is usually called a
bnard. If the piece be less in
width than 6 in., and not thin
enough to be called a board, it is

ed a j»i
., it is

commonly called a*

termed a joist. If thicker than

6 in

timbf

PLATE. The horizontal piece
of timber that lies immediately
on the top of the posts of a frame,
or on the top of the walls of a
brick or stone building. Oatter-
platKs are pieces of timber framed
out from the side-walls for the
support of the gutter.

PLATFORM. An assemblage
of timbers laid in a horizontal
position, and covered with planks
or boards, like a floor.

PLUMB. A line perpendicular
to, or at right angles with, the
horizon. A level line and a plumb-
line form a right angle when they
are brought in contact. Hence,
if one of the blades of a carpen-
ter's framing-square be placed on
the edge, in a level position, the
other blade, being at right angles
with it, will be a plumb-line.

PLUMB-RULE. An instrument
for determining plumb-lines.

POST. Any piece of timber
used in a vertical position to sup-
port a superincumbent weight, or
to support the horizontal timbers
in the frame of a building

PROTRACTOR. Aninstru-
ment for laying down angles.
They are usually made of brass
or German silver.

PUNCHEON. Nearly synony-
mous with post. It also denotes
the short studs in a partition over
a door. The word puncheon pro-
perly designates an upright post
or arbor in any machine which
turns vertically; as a crane, for
instance.

PURLINS. The horizontal
pieces of timber which lie on the
trusses of a roof, and support
the common rafters.

Q.

QUEEN-POST. A suspension-
post in a trussed roof where two

GLOSSARY.

175

posts are employed in the truss
instead of one, as is the case with
a truss framed with a king-post.

E.

RABBET. A recess, or channel,
cut into the arris of a piece of
wood. A channel cut into a plane
surface is called a groove.

RADIUS. The semidiameter of
a circle, or the length of a right
line drawn from the centre to the
circumference.

RAFTEKS. The inclined tim-
bers of a roof, which support the
covering. Those forming part of
a truss, and which support the
purlins, are called truss-rafters.
The smaller rafters to which the
boards are nailed are called com-
mon rafters.

RAIL. A term in architecture
of many meanings, but .denoting
more particularly any timbers or
pieces of wood, in the rougher
kinds of work, lying in a horizon-
tal position, as in fences, &c.

RELISH. A term denoting the
piece cut out between two tenons
existing on the same piece of
wood; also a piece cut from the
edge of a tenon when it would be
too wide if its whole width were
left.

RESISTANCE. The power or
quality in a body which enables
it to avoid yielding to force or ex-
ternal pressure of any kind, and
which lessens the effect of the op-
posing power; as the resistance
of water to the motion of a ship,
or that of wood to the operation
of a cutting instrument. The fol-
lowing table exhibits the degree
of resistance to pressure in the
more common kinds of woods,
taking common New-Jersey free-
stone as the unite —

Freestone 1

Alder, Birch, or Willow ... 6

Beech, Cherry, Hazel 6|

Holly, Elder, Pear, and Apple 7

Walnut, Thorn 74

Elm, Ash 8*

Box, Plum, Oak 11

The resistance of lead by the same
unit is 6^; brass, 50; iron, 107.

RIB. A curved piece of wood
I used for supporting the lathing
I and plastering of a vaulted ceil-
I ing, or the boarding of a dome.

RIDGE. The highest line of a
roof at the angle made by the
meeting of the top of the rafters.
The piece of wood against which
the top ends of the rafters bear is
called the ridge-piece, or ridge-

P<RIGHT LINE. The shortest
line that can be drawn between
two given points.

ROD. The term literally signi-
fies any thing which is long and
slender, and may be used to de-
note either a piece of wood or me-
tal. It denotes also a measure of
i length, being 16i ft.

ROLLS or ROLLERS. Plain
; cylinders of wood used in moving
! large timbers or other heavy ma-
! terials. They are usually from 3
! to 10 in. in diameter, and from
! 1 to 6 ft. long. To move one end
; is called cutting the roller.

ROOF. The exterior horizontal
covering of a building.

ROOFING. The general assem-
blage of timber and other mate-
rials which compose 'the roof of a
building.

ROTUNDA. A building round

on its exterior and interior, as the

Pantheon at Rome. The term is

often used, however, to denote

any large circular room the ceil-

i ing of which is arched like a

\ dome. The large room beneath

the great centre dome of the Ca-

i pitol, at Washington, is commonly

called the RutunUa.

SAG or SAGGING. The bend-
ing or yielding of a stick of tim-
; her between the points of support
when the timber lies either in a
horizontal or an inclined position.
SALLY. A projection of any
kind. In carpentry, the term de-
! notes the end of a piece of timber
! when cut to an acute angle, ob-

176

GLOSSARY.

liquely to the fibres of the wood.
For example, the lower end, or
foot, of common rafters, where
they are connected with the plate ;
the end of a stair-carriage, &c.
The outer point is called the toe ;
and the inner point, the heel.

SAW-PIT. The pit, or excava-
tion, over which timber is sawed.
Formerly the labor was done by
two persons, one standing in the
pit, and the other on the top of
the log. The men who performed
the work were called sawyers.
This work is now done by ma-
chinery ; and, fortunately for the
carpenter, he is now seldom called
upon to render so laborious a ser-
vice as that of sawing logs by the
severe and slow process of hand-
labor.

SCAFFOLDING. An assem-
blage or structure of joists and
boards, or planks, used in erect-
ing or decorating the walls of a
building. Scaffoldings are usually
built by first erecting joists in a
perpendicular position, at suita-
ble distances apart, and nailing
boards to the outside of them at
distances of every 6 ft. in height,
in a horizontal position, and pa-
rallel to the walls of the building.
The joists are called stage-poles;
and the horizontal boards, ledgers.
At every pole, and at right angles
•with the ledgers, are other boards,
continued in from them to the
walls. The last-named pieces are
called brackets. These are covered
with a floor of boards, simply laid
on the brackets without nailing.
The word stagin g is often, though
improperly, used among workmen
for scaffolding. A kind of scaf-
folding is sometimes used in the
erection of wooden buildings,
which consists of what are termed
wooden jacks ; they being confined
to the walls by means of a bolt,
with a nut on the inside. The
jacks support boards, forming a
floor as in a scaffolding, with
brackets and poles.

SCALE. An implement for
measurement. Scales are usually
made on wood or metal, and are
of three kinds; viz., the plain

scale, the Gunter^s scale, and the
diagonal scale. The plain scale
contains simple divisions of any
required dimension. The Gunter's
scale is marked by various lines
and numbers, by which, with the
aid of a pair of dividers, many
questions in arithmetic and prac-
tical geometry are readily solved:
it is usually 2 ft. long and 2 in.
wide. The diagonal scale is formed
by dividing its width into a cer-
tain number of parts, and then
drawing diagonal lines across
them. By this implement, mea-
surements may be made with
great exactness. The word scale
also refers to the magnitude of a
drawing, map, or other object, as
compared with its original.

SCANTLINGS. A term some-
times used to denote small tim-
bers; as joists, &c.

SCARFING. The joining, or
splicing, two pieces of wood, so
that the whole may appear as but
one piece.

SCRIBING. Fitting the edge
of a piece of wood to the surface
of another.

SECTION. A geometrical rep-
resentation of a part of the inte-
rior of a building as cut by a
vertical or horizontal plane. A
section not only exhibits the lines
where the separation is made, but
also the elevation of those parts
of the building exposed to view,
if the nearer sectional part was
actually removed. A longitudinal
section is one on a line with the
length of the building; a trans-
verse section is one on a line with
its width, or across it; and a ho-
rizontal section shows the floors,
being usually called the plan.
The term section also denotes a
part, or portion, considered as
separate from the rest.

SEGMENT. A part or piece
cut from any thing, particularly
the portion contained between the
chord and arc of a circle.

SEVERY. A compartment or
division of scaffolding.

SHAKE. A crack, or fissure,
in wood, caused by its being dried
too rapidly. A piece having many

GLOSSARY.

177

slits, or clefts, is said to be
shaky.

SHORE. A prop, or brace,
standing in an oblique position
against a wall to retain it in its
proper place. To " shore up a
wall " is to put shores against it.

SHOULDER. The plane at the
tenoned end of a stick of timber,
which is transverse to its length,
and at right angles with the tenon
projecting from it.

SILL. The lowest principal
piece of timber in the frame of
a structure which lies in a hori-
zontal position.

SITE. The situation or lot of
land on which a structure stands.

SLEEPERS. Pieces of timber
which lie horizontally on the
ground, under the principal tim-
bers of a ground-floor.

SLIDING-RULE. One haying a
figured slide, which, being moved
against logarithmic lines, deter-
mines various arithmetical calcu-
lations.

SOCKET-CHISEL. Same as
firmer-chisel.

SPAN. The distance, or spread,
between the eaves of a roof, the
abutments or piers of a bridge,
&c.

SPAN-ROOF. A roof consist-
ing of two simple inclined sides
in contradistinction to shed-roof.

SPIRE. That part of a steeple
which diminishes as it ascends.
Any tapering body.

S'PLAYED. A term denoting a
side which makes an oblique angle
with that adjoining. The jambs
of a window are often splayed;
thus, by making the aperture
larger in the room, admitting
more light.

SQUARE. A figure of four
equal sides, and as many right
angles. Also an instrument used
by carpenters and joiners for lay-
ing out and squaring their work.
(?ee CARPENTER'S SQUARE.) A
thing is said to be square when
its angles are right angles.

STAGE. A floor on which
actors perform in a play-room.
In ancient theatres, the stage was
culled the proscenium. This term

in modern times denotes more
particularly the front of the stage
at the line where the curtain fells.

STANCHION. A prop, or sup-
port. The term is nearly synony-
mous with post.

STARLINGS. An English term
denoting piles driven about the
piers of a bridge, or the sides of a
timber- wharf, to give them sup-
port.

STAY. Any thing performing
the office of either a tie or a brace,
which prevents the swaying of
the work to which it is affixed.

STEEPLE. The lofty erection,
! ending in a point, which sur-
| mounts a church. It is composed
of a tower and spire. The tower
extends from the ground to the
line where the steeple begins to
diminish. From this point, the
remainder is called the spire.
Where the edifice has a porch or
projection in front, the steeple is
considered to begin at the top of
the porch named.

STORY. That vertical division
of a building occupying the space
from the top of one floor to the
under side of that immediately
over it. A building is said to be
as many stories high as there are
alternate spaces of this description
from the top of the sills to the
top of the plates at the eaves.
In America, the principal story is
usually on the first floor : in Eng-
land, it is on the second. In this
country, we usually denominate
the first story above the ground
the principal or entrance story ;
that above this, the chamber-story ;
and those above them, the third,
fourth, fifth stories, &c.

STORY-POST. A post between
two adjoining stories of a building,
for supporting a superincumbent
weight.

STRAIN. The force exerted on
any material which tends to de-
stroy the cohesion of its parts.

STRAINING-PIECE. A piece
placed between two opposite pieces
of timber to prevent their nearer
approach. It is always in a state
of compression.

STRAP. An iron plate, bar, or

12

178

GLOSSARY.

band for confining together two
or more pieces of timber.

STRIATED. Marked with
small furrows, or channels, as
those in a piece of wood sawed by
a large saw in the direction of its
length. When, in sawing lumber,
the saw is not firmly fixed in the
frame, the sides of the timber are
made rough or ridgy, and are then
said to be striated.

STRIKING. This term denotes
the act of lining out, or marking
off the surface of any piece of
timber, for making mortises, te-
nous, &c. ; also removing the cen-
tering on which a vault or arch
has been built.

STRUT. This term is nearly
synonymous with brace; and, if
it may be more properly used in
any case, it is when it denotes a
timber designed to keep extended
those parts of the work against
which its ends come. The term
brace may be used as a substitute
for strut, but not strut for brace.
A strut, therefore, is always in a
state of compression, while a brace
may be either compressed or ex-
tended.

STUBSHOD. A term in com-
mon use among carpenters and
joiners to denote the roughly split
wood at the end of a piece of tim-
ber, not sawn through, but split
or cleft apart, after the log was
removed from the track over the
saw-pit.

STUDS. Those short timbers,
or joists, framed into the sides
and ends of wooden buildings to
complete the framing of the wall.
Those at the sides of windows are
generally made somewhat larger
than the rest, and are called win-
dow-studs : those cut in, under, or
over the braces are called jack-
studs. Of late years, the term is
used to denote also those timbers,
or joists, called partition-studs, to
which the lathes are nailed in par-
titions. In England, partition-
studs are usually called quarters.

STUFF. This word is used by
carpenters and joiners to denote
indiscriminately lumber of any
kind. Lumber, sawed to any par-

ticular size or dimension, is called
dimension-stuff. It is to the car-
penter and joiner what the gene-
ral term stuck is to other me-
chanics.

SUMMER. Any large beam
designed to cover a wide opening.
A small summer is called a lintel.

SUPER.VI'RUCTURE. That part
of an edifice erected above the

T.

TAIL-TRIMMER. A piece of
timber, into which the ends of
joists are framed, where chimney-
flues, or any thing of like nature,
prevent the insertion of the ends
of the joists as may be done where
the wall is solid.

TAPERING. A term denoting
that the sides of a body gradually
approach each other in the di-
rection of their length; so that,
if continued, they would meet at
a point.

TEMPLET. A short piece of
timber laid under the end of a
beam or girder in the walls of
a brick or stone building.

TENON. The end of any piece
of wood so reduced as to fill and
fit into a mortise. The tenon pro-
jects from the rest of the wood;
and the place where it commences
is so cut as to form a surface at
right angles with it called the
shoulder.

TENSION. The stretching or
degree of extension to which a
thing may be strained in the di-
rection of its length.

THRUST. The force exerted
by one body against another; as
that of a segmental arch against
its abutments, or the rafters of a
common roof against the plates.

TIE. A timber, chain, or rope
so fixed as to retain two bodies in
a particular position when a ten-
dency exists to diverge or spread
apart.

TIE-BEAM. The beam at the
foot of a pair of large rafters,
serving to tie the walls of the
building together by counteract-

GLOSSARY.

179

ing the thrust exerted by the
rafters named.

TIMBER. This term is used so
indefinitely, that it is a matter of
some nicety to lay down any defi-
nition which will not clash with so-
called " well-established usage."
The true meaning of the word
seems to be wood fit for buildings.
And, as used at present, it denotes,
1st, The trunks and larger limbs
of trees either standing or cut
down ; 2d, All large sticks, after
they are sawed or hewn out, and
squared for use.

TOE OF A RAFTER. The ex-
treme point of a rafter, after it is
so cut at the end that it may fit
on the plate. The inner point is
called the keel of the rafter.

TOEING. An expression de-
noting a nail, or other article,
driven diagonally through one
piece of wood to confine it to
another. Nails are driven toeing
into wood, when, from the pecu-
liar form of the piece and the dis-
position of the parts to be con-
fined together, it is difficult to use
the nail at right angles.

TORSION. The strain on any
material which tends to cause the
same to twist or wind.

TRANSVERSE. A cross direc-
tion. The transverse strain on a
piece of timber is when the force
is so applied as to break it down
when it lies in a horizontal posi-
tion.

TRAMMEL. An instrument
for describing an ellipse, or oval.

TRIM. To fit or prepare any
piece of wood so as to make it
suit another. To make a tenon
smaller, that it may fit into a
mortise, is to trim it up.

TRIMMER. A small beam into
which is framed the ends of floor-
joists at an opening in a floor.
The joists into which the ends of
trimmers are framed are called
trimming-joists. Trimmers are
used at the sides of well-rooms, of
stairs, against chimneys, &c. The
last are usually called tail-trim-
mers.

TRUNCATED. A term denot-
ing that the top or apex of any

thing Is cut off. The part that
remains is called the frustum. A
hip-roof, the rafters of which do
not continue up to a point, but
end against a framed platform, is
said to be truncated.

TRUSS. A peculiar combina-
tion and arrangement of timbers
hi framing, whereby they are
made to mutually support each
I other.

TRUSSED PARTITION. A
partition having a truss within it.
i Partitions are trussed when, from
j the arrangement of the rooms
I under it, a support cannot be
! given from below without inter-
fering with the clear space of the
i room.

TRUSSED BEAM. One con-
i taining the principles of a truss.

TRY. To plane out a piece of

; wood true and square. The act

of squaring wood by the plane,

preparatory to putting the work

together, is called trying it out.

TUSK. A bevelled shoulder
made on the end of a piece of
framing-timber above the tenon.
j The tusk is framed into the beam
or girder, and is designed to give
additional strength to the tenon.

TJ.

UPHERS. An old term denot-
ing small poles or sticks of tim-
[ her partially squared. They were
used for scaffolding, common roofis,
&c.

V.

VALLEY. The line at the in-
ternal meeting of the two inclined
sides of a roof. The rafter under
i the valley is called the vaUey-
I rafter.

VAULT. An arched roof or
! ceiling over an apartment.

VAULTED. Arched like a vault
I or the interior of a dome.

VERTEX. The point of termi-
nation of any thing, the sides of
which are inclined and continued
till they meet; as a cone or a
common roof.

180

GLOSSARY.

w.

WALL. The sides or ends of
any building or apartment.

WALL-PLATE. A piece of
timber placed horizontally on the
top of a wall. The term plate de-
notes the same thing.

WEDGE. One of the five me-
chanical powers. It has five sur-
feces; is thick at one end, and
slopes to a thin edge at the other.

WELL-HOLE. The open hole,
in a flight of stairs, at the end of
the steps.

WICKET. A small door made
through a larger door or gate.

WINDLASS. A machine for
raising weights. It consists of a
strong cylinder of wood or iron,
which moves on an axis, and is
turned by a crank, or by means
of levers inserted in mortises cut
into the outside of the cylinder
near the ends. Around the cy-
linder is wound, by its revolu-
tions, a rope or chain, the other
end of which is attached to the
weight to be raised. The wind-
lass is used in a horizontal posi-
tion. The capstan, an instrument
of the same nature, is used up-
right. (See CAPSTAN.)

THE END.

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